Bonsai & Bleeding Trees

Bonsai & Bleeding Trees.


A little lesson on grammar and the English language with a healthy dose of personal opinion mixed into my experiences of bleeding bonsai trees.

Warning: Contains strong language and personal opinions. If you are easily challenged or offended please f’ off now.

Look up the word bleeding in the British English slang version of its usage and you will find it’s an adverb used as an intensifier. As an example, were I to describe someone as stupid but needed to add additional weight or offence to my opinion I could add the word bleeding as a precursor. Collins dictionary lists seven explanations for the word with the primary definition being the act, fact or process of loosing blood. You’ve just got to love the English language.

Bonsai & Bleeding Trees

Bonsai & Bleeding Trees. Tis but a scratch!

Sadly, in this day of ‘alternative facts’ language is being messed with on an unprecedented scale. Just yesterday (Monday) the almighty and holy BBC reported that oil prices rose sharply on news of the recent conflict that’s kicking off. Apparently that’s going to lead to another pump price increase. On the face of it all sounds reasonable right? However for the previous 11 days the price had been falling quickly from $94.3 to $84 but they picked up on the fact that it jumped $4 a barrel (Brent) to $88. So they were right the price did rise but overall it fell when looked at in the context of a few days. Seems like everyone wants a sizzling headline whilst the actual facts are irrelevant.

Another area where understanding is being lost, or at least confused is in the act of conflation, the merging of two or more sets of information into one. For instance nuclear generation of electricity being labeled as clean green energy. It might produce relatively little carbon pollution at the moment of generation but in all other respects it’s as grubby as a teenage boys under-crackers. 

Our English language has a huge and easily mis-understood vocabulary, by some estimates over a quarter of a million words most of which we will never use (or possibly understand) but, by and large we work on the basis that if something sounds right we generally believe it. After all figuring out the truth takes some effort.

For example climate change, sorry i’v got to get this out there. “They” recon it’s all our fault for driving cars and heating our homes with the fuel ‘they‘ provided for us. That means 1.47 billion cars need to be replaced along with practically every other piece of electrical and industrial equipment on earth and that has to be done without using oil or coal. Are these folk fucking mental? I’m about to be 60 years old so have limited experience and they may well be right, however the postulation that climate is stable appears (to me) flawed even though it’s presented as the bedrock upon which all this BS is founded.

Seeing as the area i am currently sitting in was, supposedly once, both a warm tropical sea and a glacial till plain it strikes me the climate is prone to change from time to time. For sure the exploitation of oil has allowed the human race to burgeon way beyond anything that is either sustainable or sensible. Ultimately the conflation of virus like human multiplication and tiny increases in average temperatures have given rise too, possibly the largest and most lucrative money and power grab in our history.

Ignoring the fact that we cut down all (or most) of the worlds trees over the last couple of millennia. And conveniently ignoring the fact trees lift moisture to cool the atmosphere (as we will see later), create cooling shade, trap moisture and light, collect carbon and produce oxygen, alongside our once healthy seas it’s YOU and I that fucked it all up with our cars and gas boilers. I could rant about this shit show for a month but best I just offer this as an example of how conflation can lead us up a blind alley. Time will tell.

We live in one of the greatest times in human history and have the assembled knowledge of the entire human race at our fingertips. So, what exactly are we doing with that? Looks to me like not a lot, getting at crossed purposes with folk, causing conflict and in many instances becoming more stupid……bleeding stupid by the day. I while away many happy hours with a herf at my local old school motorcycle shop where the conversation revolves primarily around two subjects, everyones medical woes and the stupidity of youngsters and folk not in the room. My friends, ignorance abounds.

It’s so easy to find stuff out today but sadly so many of us just don’t bother, we’re all guilty of taking the easy route much of the time. However real knowledge is a hard won thing, especially where that’s learnt through life experience. Like the BBC’s fuel price shocker, it might be true but reporting that fuel prices spiked without the context is at best deceptive and misleading and will cause considerable angst among some already hard pressed folk trying to make ends meet.

Bonsai & Bleeding Trees

So what’s all this got to do with bonsai? Bleeding bonsai, or more specifically trees that bleed when they are pruned. Over the years I have had a lot of discussions with folk over the subject and thought it might be helpful if I put what I have learned down on paper or to be precise pixels.

Liquids flowing out of our trees generally cause a little panic. This typically happens in spring around the time leaves begin to appear and follows damage of some kind like pruning. Liquid running out of a tree raises the spectre of a slow but imminent death because we have made an unconscious conflation between our knowledge of animals having a limited amount of blood and applied that to our bonsai tree. Cut a good lump off most animals, including ourselves and in pretty short order the heart will pump our veins and arteries dry leading to oxygen starvation with obvious consequences. 

Trees are different, they don’t have hearts, veins, arteries or limited blood supplies. The amount of liquid available to a tree can be large because it’s water from the soil. Trees do not rely upon a single organ (lungs) to absorb oxygen or a liquid like blood to distribute that oxygen to its extremities. Trees are able to absorb air, including oxygen through their leaves and external bark, including the roots so all parts of a tree are independent of other parts for oxygen supply.

So why do trees bleed? Does bleeding affect or weaken a tree? Does bleeding indicate declining health? How can it be prevented or treated? In order to answer those questions we need to understand exactly what’s going on.

A tree, including a bonsai tree, is a naturally closed hydraulic system. Water is absorbed from the soil into the roots via osmosis where it slowly moves through the plant to the leaves where a small amount is combined with carbon dioxide and made into sugars. Up to 99% of the water absorbed by the roots evaporates into the atmosphere by a process known as transpiration.

Movement of water from soil to roots to leaves is driven by two forces or ‘pumps’, one in the roots and the second in the leaves. These are connected by fine tubes, xylem vessels in broadleaves and tracheids in conifers which extend throughout the entire plant.

Water only rises through the tree in the outer edge of the woody material, the xylem. The remainder of the trunk is actually dead and serves as the supporting structure for the living part which is why a tree can be hollow but still live happily for centuries. The water rising up a tree is commonly known as sap, a solution of mineral salts in water all drawn from the soil.

In late winter or early spring this sap is enriched with sugars released from storage in the roots and used as energy for initial leaf and shoot formation. Maple syrup anyone?

Bonsai & Bleeding Trees

Bonsai & Bleeding Trees – Not a recognised bonsai technique.

Osmosis happens when water moves from a weak solution in the soil through a semi-permeable membrane, the root cell wall, into a more concentrated solution within the cell. Water entering the roots in this way creates a tiny pressure which forces water up through the xylem tubes into the tree. Further movement is assisted by capillary action in the very fine xylem vessels that are connected from the finest root to the last leaf.

Evaporation from the foliage forms the second ‘pump‘. As water evaporates from the leaf more water is drawn in to replace what’s lost via the xylem. An unbroken hydraulic column of water is formed right from the fine feeder roots to the very last leaf. The leaves will wilt if water evaporating from them is not replaced as required. A prolonged water imbalance results in leaves withering and ultimately dying off which reduces the plants water needs and hopefully returns everything to a balanced state. Young trees have little defence in this situation but older mature trees are significantly more robust.

Evaporation from leaves increases with warming temperatures and warm air movement. We all know watering is required more often in summer unless you live in an area that is so warm and humid that evaporation ceases in which case water usage is minimal, not a problem in Blighty. Here cooler wet days reduce transpiration and may see our trees almost stop absorbing water from the roots, especially when it’s raining or misty as water can be drawn directly into the leaf thought the stigmata or should that be stomata?

In dormant leafless trees evaporation from the upper part virtually stops but roots remain active. Evergreens need to replace small amounts of moisture lost through their foliage. Whenever the soil temperature rises above freezing roots will be busy absorbing water until the weight of the column of water within the tree is equal to the force exerted by osmotic pressure and balance is achieved.

The resultant pressure of water within the roots ensures that water carrying channels are full and primed to supply water needed to swell buds, leaves and shoots as soon conditions are suitable for growth to begin.

With positive water pressure within the tree any damage, for example pruning, may release pressure and allow sap, normally a colourless watery liquid, to escape. We call this ‘bleeding‘ because it looks a lot like what happens when we suffer injury, we spring a leak. However the conflation of leaking sap and blood are as relevant as pissing and a punctured tyre.

This leaking process, trees that is, can continue for many weeks as long as there is water available to the roots to continually add to the flow. However bleeding usually stops once new leaves have grown and evaporation begins to relieve the water pressure within.

Bleeding, following wounding, is not inevitable, not all tree species bleed. Evergreens tend not to bleed as a small amount of evaporation from their foliage helps relieve sap pressure. On the other hand maples or birches can gush sap for weeks. A trees response to wounding varies with the time of year and when damage occurs. In most broadleaved species the serious risk of bleeding is in winter and early spring just before buds open as the internal pressure is high.

Not all damage will result in bleeding. For instance where the trunk of a conifer is grazed, removing an area of bark but not damaging the underlying wood the tree may ooze a sticky resin in an attempt to re-seal the effected area. Where damage breaks the capillaries, the xylem vessels, there can be a release of watery sap.

Late winter or early spring pruning, particularly of deciduous trees, is the most common cause of bleeding simply because the sap pressure will be highest then and a prune will normally sever the xylem vessels. Very sharp scissors will make the bleeding worse because so many capillaries will be left open ended. In order to prevent the possibly distressing sight of your bonsai tree bleeding profusely it’s best to do your pruning in autumn (which may not always be advisable on all species) or late spring just as the leaves begin to open. Personally i’m not squeamish and far from bothered about gushing sap bleeding out of my charges and in over thirty five years mucking about with all this I am yet to see a single example of a problem directly attributed bleeding.

It’s a natural reaction to try and stop our tree bleeding following pruning. However in my experience, regardless of what’s used to try and seal a cut, the product will be at best ineffective. Conventional putty type wound sealers are easily pushed off by sap pressure. Water based sealers like Kiyonal tend to get diluted and washed away. Oil based paints are simply circumvented. I have seen folk try to cauterize a wound with a flame of some sort, this may be temporarily effective but sap will soon begin to flow again through a wound that will now be larger than it was at the start. My advise is DON’T BURN TREES!

Some bleeding from a cut may be beneficial in keeping the wound free of infection. Bleeding will stop once new leaves appear and sap pressure is reduced. If this whole thing bothers you the best cause of action is to avoid pruning in late winter or early spring. Now I realise that’s not always convenient or desirable and should a spring trim be required I would suggest allowing the trees soil to dry out for a few weeks prior to working. This slight drought should reduce sap pressure a little and reduce the sap flow. I should caution, do this carefully as it’s possible to do more harm than good.

We know that water moves upwards within a tree however there is significant evidence to prove that it can also move downwards too. Experiments on the desiccation of nursery stock have proven that water can be drawn out of roots and back into the soil where the growing media becomes critically dry. That’s not unlike fertiliser burn which causes reverse osmosis. In bonsai controlling soil moisture is something we have to become ‘past masters’ of as I discussed in my recent post on – How To Stop Killing Bonsai Trees – Thoughts On Winter Care.

Very occasionally it’s possible to find the leaves of a tree bleeding sap. Typically this happens in summer when the conditions are nicely warm, very humid and the air is still. Droplets of water can be seen on leaf edges. This is not the result of wounding, it’s an indication of excess water pressure within the tree caused by excessively wet soil conditions favouring rapid absorption from the soil whilst evaporation from the foliage is very limited by conditions. This process is called guttation and is a common phenomenon in temperate areas where conditions are warm and humid. The phenomenon is more commonly seen in species with toothed leaf edged like elm varieties. Guttation is very common in tropical species like ficus.

As mentioned earlier conifers don’t tend to bleed sap in the way deciduous trees do. Where a conifer is damaged it will typically exude a sticky resin. Where wood boring insects enter conifers the tree will flood the area with resin that will seal the wound but will also trap and kill the offending intruders, that’s how we get insects trapped in amber which is just fossilised tree sap. Once the resin solidifies the wound will be permanently sealed and protected. In general conifers don’t bleed resin for no reason, it’s almost always a response to an attack by something undesirable wether that’s an insect or a knucklehead with carving tools. 

Resin leaks from bonsai can cause a problem in as much as they look bad. A slick of sticky resin down a trees beautiful craggy bark can ruin the appearance of a beautiful bonsai so be careful where you go cutting, choose the time of year appropriately and go little by little. In the past I have seen resin run out of conifer for more than a year. That made a hell of a mess and in the end the only way I got it to stop was isolating the exact point of the leak and then using a flame to boil the resin which did stop the flow once it cooled. Cleaning resin from bark or deadwood in bonsai is not easy but it can be dissolved using turpentine. Do not use white spirit, that’s made from oil whilst genuine turpentine is made from distilled tree sap. Methanol (methylated spirit) may also be effective. DO go easy with this as either could prove toxic to you or the tree used inappropriately.

To sum up, sap bleeding from a wound or guttation from leaves is not normally harmful. However do bear in mind the sap will contain a weak solution of sugars and whilst this may not be detrimental to the tree, even over several weeks it could be possible to cause weakness if one continues to cause extensive bleeding year after year. Also bear in mind sugary sap can attract insects or fungal moulds if allowed to dry on the tree over an extended period if rain does not wash the sap away from time to time. There is always a reason why a tree may be bleeding sap and if it’s happening spontaneously a careful investigation into the cause should be made.

I’ll give the last word here to Walter Reeves from Georgia

River birch tree sap is known to cause babies to be born naked and to make your hair turn grey when you’re old. Other than that, the sap that is dripping from the cut branches is harmless. 

Thanks for reading. Please share if this has been helpful 😉

Graham Potter

October 2023

How To Stop Killing Bonsai Trees – Thoughts On Winter Care

This gets a bit long, if you are in a hurry you can skip the preamble….

Preamble – BS for starters

Before I get into todays main course please allow me to apologise for the lack of blog posts so far this year. I don’t have a precise explanation for my absence. In modern parlance I feel I have been suffering from what’s known as an acute mental health crisis. That might sound serious because that’s how modern society likes to use language. Back in the days of plain English we would say I’ve been a bit naffed off, fed up or depressed.

Yesterday I fell off a ladder and am a bit banged up so here I am making the most of my straitened mobility.

Now I know a great deal of you lovely people look forward to my ranting, raving and spouting bollocks and I am truly sorry to have deprived ya’ll of a smile but honestly I have been moments away from throwing in the towel this year. I have been ready to close our doors and get a job delivering groceries.

In the words of the immortal Larry Love – Alabama 3 – Terra Firma Cowboy Blues
The world don’t seem to fit me
I’m always starin’ at the stars
A better life for me in some other galaxy
I wanna get off this world of oursI got a telescope on the roof
I’m always searchin’ the stratosphere
’cause breathin’, breathin’ it ain’t easy
In this loveless atmosphere

WTF happened to my country? Great Britain was once the envy of the world or some parts at least. We invented most things and perfected the things we didn’t invent. We largely, by some measure, invented modern civilisation and stood up for its values (with a few inevitable blind spots). We even gave the world our language and now we seem to have literally flushed the lot. We’re in such a f**ing mess our idiot leaders can’t even decide how many genders the human species contains.

Sadly I’m not the sort of bloke to just laugh this all off and when government regulation and rules have cut my livelihood in half I take the situation as seriously as a heart attack. Britons are literally drowning in liquified bullshit and most folk appear to be asking for seconds. Just don’t ask for a straw or plastic spoon, they’ve been banned. If you go to a regular job and spend your time looking at sport I guess life is pretty good. Thumbs up if that’s you, salute!

Personally I have no time for sport. I have never watched a football match in my entire life and the only ‘sport’ i got into for a short while was F1 (IMHO now a load of tosh) but trying to get sports removed from my Sky package this year was almost impossible. I told the guy on the phone I want it removed entirely and after fifteen minutes of refusing my request he’s like “Why wouldn’t you want to watch sports?” In the end I had to say “look you cloth eared c***, you either remove sports or I will cancel my package entirely, then I’ll come over there and shove this box up you hole personally.” Obviously that went down well with a retort along the lines of ‘no need to take that tone’. After an hour and a half I got what I wanted but now they call me up every few days and ask if I would like to get it back. Take my advice, give Sky a wide berth if you can.

Here’s how I lost another 2 hours of my life last week. These days I drive old school Toyotas, the type with a heavy steel chassis and over-engineered diesel engines that do a million miles between oil changes, they don’t break down, but for my good lady’s peace of mind we have, for over fifteen years, paid the AA for breakdown and recovery services. In all those years I have called them out twice, once when my old beater of a Mercedes van wouldn’t start out in the middle of the woods and another time when Catherine’s Mini (BMW) went to shit. I now no longer have German vehicles.

It’s a little known fact that Stonehenge was actually built using a Toyota Hi-Lux. Forget all that Tony Robinson crap about wooden rollers, boats and dragging stones across from Wales, that’s a crock, the Japanese were well ahead of the game as always. The only reason the boffins don’t know this is that they never found it, it’s still running about the middle east with a 50 cal’ bolted in the back. Had the builders used a Mercedes the rotting husk would have been found in the bottom of a deep pit round the back along with the detritus of packed lunches, broken Thermos flasks, busted shovels and well thumbed tatty copies of Mayfair and the Daily Sport.

One of the most influential factors in human development. The Toyota Hilux!

So, I get my renewal through and it’s about £275 because I am their longest standing customer and they really value my loyalty. Now I remember when this cost a fraction of that sum and when I inquisitively look online new members are getting the same cover as me but for just £108. You know what comes next right? I get on the blower and after what seems like a very long time a chipper young fellow answers my call.

I raise my issues but he tells me i’m wrong and my renewal figure is what it costs to actually run the service…..that I don’t ever need to use. So after some back and forth he’s not so chipper any more, I can have that effect on people. I get him to back down and he offers me £50 off which I politely decline. Now I’ve got him on the run I muster the big guns, this is fun and my renewal price ends up at the £108 I can get online as a newbie. He’s so chuffed he got me over the line but my opinion is that if he can offer the service for that figure that’s what it should be all along right? I really don’t appreciate their pissing up my back and telling me it’s raining. I kept them on the phone for 2 hours and never renewed.

The AA are a conning bunch of robbing bastards even if their breakdown service is pretty good in my limited experience. And, just to put a cherry on the cake today I got a letter offering me the service for £39. When I looked into that it actually cost £59 but you get a voucher worth £20 for a posh shop I never use because i’m working class. I remember when the AA was a respected organisation and a British institution to be proud of. I recon they’re a bunch of chiseling grifters these days. If you happen to work for this once august institution i’m sorry.

My glass has never been half full, but this sort of experience is now the norm in our country. Everything is geared towards big business and us little guys just don’t stand a chance. I’m not even going to get into our so called ‘government’ who are hell bent on controlling everything and taking care of nothing. They shit on my head whilst telling me it’s a fashionable new hat the’ve provided for me entirely free which is cool right? But what CAN the little guy who didn’t go to the right school or descend from the right bloodlines do? Well I can spout on about bonsai trees for a bit….

How To Stop Killing Bonsai Trees – Thoughts On Winter Care

So, it would appear I have gotten off track somewhat. My original intention was to put together my thoughts on how folk have been losing lots of bonsai trees this year so here goes……..

I have seen and heard a considerable number of what we might politely call ‘bullshit theories’ alongside some insightful but occasionally ill-thought out conflations about what’s been going on. It’s not just us bonsai folk, right across horticultural disciplines heavy losses have been seen. My only concern is that we learn what we can and not in a “Join the AA for just £39 or £275 for the exact same service” type of way.
So for what it’s worth here’s my two penn’orth……

Anyone remember to winter of 2010/11? It’s actually got a dedicated Wikipedia page. That was a cold one here on the normally mild east coast as relentless onshore winds cut us all down to size but across the whole country it was flippin’ taters. Bonsai tree losses that year were off the scale catastrophic. Previously we had more than ten years of largely mild winters and most of us were lulled into a sense of false security and marginally hardy trees like tridents, Chinese elm, Japanese black pines and Mediterraneans were left outside where, as it happened, they froze to death. I know folk that lost tens of thousands of pounds worth of the most amazing bonsai trees.

During the autumn of 2010 a bargain fell into my lap in the form of a massive ancient cork bark Chinese elm. I picked it up locally for a song and it filled the back of my van. This was a spectacular tree and the best of it’s kind I personally have ever seen. With my then limited experience of the variety I just left it outside for the duration. The tree never came back into leaf and ended up in my log pile and it broke my heart. However I know for a fact it had spent many years outside further inland where it’s always colder in winter than it is here on the coast so what gives?

Come summer of 2011 it was literally impossible to sell trees of any type, the whole community seemed to be reeling from heavy losses and were too shaken to start filling up their benches once again. Confidence was severely undermined and it took all of us a long time to get over what we had experienced. However we largely have short memories and by the following year everything was back to normal though lots of folk set up overwintering facilities which were largely not needed as winter temperatures returned to normal.

This last year was an odd one and that makes it hard to read or understand why problems have been so widespread. Certainly where we live the temperatures didn’t get that low. We got -5° C where we would normally see -1°C at worst but then that’s hardly a low temperature where hardy plants are concerned. We had some wet patches too but nothing particularly unusual. Last summer was nice, warm and sunny. Forget the media hype it was a beautiful warm and sunny summer but, for heat, not a patch on what our friends in Spain or Italy experience every year and they do just fine. Most folk across the country lost something so it’s not down to the individual so what? What went wrong?

The activity of plants are dictated by light. Wiki’ states…..
Photoperiodism is the physiological reaction of organisms to the length of night or a dark period. It occurs in plants and animals. Plant photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light and dark periods. They are classified under three groups according to the photoperiods: short-day plants, long-day plants, and day-neutral plants.

What this means is that our little trees sense the daylight hours increasing in spring and begin to move into a growth phase. The rate or speed of that growth is dictated by temperature but it’s not triggered by temperature. That’s why a hawthorn may be showing red buds by mid-January when folk begin to panic and demand I send their soil by emergency courier because they MUST re-pot today. However the temperatures in January are normally what’s locally known as ‘basterd cold’ and so whilst your beloved thorn may well be showing signs of life it’s literally months away from developing proper leaves until day length and temperature increase a good bit.

Now this photoperiod is not just responsible for triggering spring growth but everything a plant does. Leaf formation, shoot extension, flowering, fruit set, secondary hardening of growth, root formation, wood production, the next seasons buds and WINTER HARDINESS are all dictated by day length. When the days are long most plants are growing for all they are worth because certainly in Blighty the summer is pathetically short and light intensity is never ideally high. As the light fades later in the year, shoots are done growing, roots are formed and the following seasons buds are in place a tree will begin to mature new growth and prepare for winter. The general consensus is that they need night time temperatures down to +5° C for a few weeks for this to kick in. What happens inside the tree varies by species and it’s too complicated for us to fuss over.

Last years nice warm summer was an absolute belter and our trees, assuming we took advantage, should have had an amazing year which based on my own experience they certainly did. Plants ONLY get their energy from the sun and a nice bright one means our trees have high energy levels and should be able to get a lot done and be tough and resistant to just about anything. However last year temperatures were high late into the autumn and then cold came in early. On the coast here temperatures never drop below freezing before mid-January onwards. Last year that happened in early November whilst a great deal of my deciduous trees were still in full leaf.

As the day length begins to shorten significantly a plant has a lot to do in a short period though to us it might not appear to be all that. Just because a tree is not growing or has no leaves don’t think for a moment nothing is going on because it IS. So, what’s happening?

A tree in full leaf stores a great deal of its energy, in the form of sugars, in the foliage. The development of fall colour happens because a tree is preparing for winter and will draw out as much valuable resource from every leaf as it can starting with the green chlorophyl. Once the process is complete most deciduous trees instigate a process known as ABSCISSION from Latin ab- ‘away‘, and scindere ‘to cut’. This causes the leaf, or fruit, to drop.
A plant will abscise a part that is no longer necessary, such as a leaf during autumn, or a flower following fertilisation. Most deciduous plants drop their leaves by abscission before winter, whereas evergreen plants continuously abscise their leaves. Another form of abscission is fruit drop, a plant abscises fruit while still immature in order to conserve resources needed to bring the remaining fruit to maturity.

Abscission occurs in a series of three events:

1) Resorption –
Resorption involves degrading chlorophyll to extract the majority of its nutrients. Nitrogen is found in chlorophyll and is often a limiting nutrient for plants, which need large quantities to form amino acids, nucleic acids, proteins, and certain plant hormones. Once nitrogen and other nutrients have been extracted from chlorophyll, the nutrients will travel to other tissues of the plant. Resorption is what causes leaves in the fall to change colour. Carotenoids in the leaves are slower to degrade than chlorophyll, so autumn leaves appear yellow and orange.

2) Protective layer formation –
Cells under the abscission zone divide and form a layer of cork like cells. Situated on both sides of the abscission zone are layers of parenchyma cells, which produce and inject suberin and lignin under the abscission zone into the new layer of cork cells. Suberin and lignin create a durable and waterproof layer for the plant once the element is detached.

3) Detachment –
This step can occur in a variety of ways depending on the species but always occurs at the abscission zone. Detachment can occur when layers of parenchyma cells secrete cell wall enzymes to self-digest the middle lamella or membrane, which holds the cell walls together at the abscission zone. This causes the cells of the abscission zone to break apart and the leaf or other plant part to fall off. Another way detachment occurs is through imbibition of water. The plant cells at the abscission zone will take in a large amount of water, swell, and eventually burst, making the organ fall off. Once detached, the protective layer of cork will be exposed and the area is protected and sealed off from the outside world.

Another thing a tree must get done before winter is the hardening off of new growth and roots. This is achieved by the formation of lignin. Lignin (woody tissue) is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Chemically, lignins are polymers made by cross-linking phenolic precursors. Simply put, soft vegetative tissue become fibrous which gives it the ability to resist the effects of freezing. This happens throughout the summer and autumn. Last year I had maples making strong extension growth throughout September and the first half of October. Most of this did not harden off fully before the frost came and as a result was lost to the cold.

By now it’s obvious there’s a lot more going on here than might appear to be the case from casual observation. A bonsai tree is a tree largely cultivated in a very un-natural situation and very often a very long way from it’s natural environment. For instance mugo pine growing in the Alps stand temperatures below -40C in winter and are often buried in meters of compacted snow. The roots are frozen solid for months on end and therefore bone dry. At sea level where, certainly in this country it’s not frozen for most of the time but it is sopping wet thanks to rain and cool conditions the roots are waterlogged for months on end and so can rot. So a tree that lives in one of the most extreme climates in Europe can die spectacularly in a soggy warm British winter which brings me neatly onto my next point.
What’s the deal with freezing? Without water there would be no plants….or any other life come to that and, much like the other ‘water of life’, in the right place it’s a great asset. However too much can be a bad thing and too much for too long is almost always a very bad thing. One can go from being lucid to ludicrous to hospitalised in a very short time much like a bonsai tree though the latter’s going to show delayed onset of symptoms.

It’s commonly stated that 50% of a tree’s weight is water. But the moisture content of different living tree species can range from 60% to 200%, where there’s twice as much weight from water as there are wood fibres. So obviously this is important.

It’s a very long time since I went to school and back when I did go I didn’t actually go very often. Even when did go to class I was far from a model student and spent my time being a right little knob. One subject I did okay in was physics, it seemed like a lot of common sense to me apart from all the equations of course. One thing they did teach me was about water, it provides a reference point for things like temperature scales etc’. That’s because it’s everywhere and very easy for folk to reference. It can be solid, liquid and gas all within a fairly narrow range ie: from freezing to boiling point.

When water freezes it expands. As a liquid the molecules huddle closely together but as the temperature falls and the water cools down, the intermolecular forces increase, the freedom of movement of water molecules decreases, and they become less and less energetic the colder they get. When water reaches its freezing point, the movement of its molecules become negligible as they take on a more defined shape, arranged in six-sided lattices. This crystalline arrangement of water molecules is less dense, as it prevents molecules from huddling up due to stronger intermolecular forces. This spacing of molecules and keeping them fixed in that position increases the volume of water, which is why it’s said that water expands when it freezes. Typically freezing water increases it’s volume by 9 > 10%.

Trees are a naturally closed hydraulic system made up of cells, think of those cells like inflated tea bags. Put a row of them together and fill one with water and before long the water will be dissipating into the adjacent ‘cells’. There is strong cohesion between water molecules because of hydrogen bonding. A continuous column of water is therefore pulled up the plants stem in the transpiration stream by evaporation from the leaves. As water travels through the xylem in the stem and leaf, it is being replaced by water taken up by the roots. When water freezes it expands putting pressure on the cell walls. If these are not sufficiently strong, as in the case of tender plants, to accommodate the expansion the cell walls rupture and the water column will be broken. Where this happens extensively the plant may not be able to repair itself or recover. The damaged area and that above it will eventually die completely.

Here’s a couple of amusing examples from my own refrigerator, a place in our house where good vegetables go to die. I recently found a bag of rather disturbingly shrivelled soggy looking carrots. Some were not rotted but could easily be bent end to end. I gave them a rinse and put ‘em in a glass of water. Two days later they were as good as new, rock hard and as firm as the day they were plucked from the ground. I ate the lot and they were good. Just like the tea bags the water soaked from cell to cell until everything was back to normal. No, i didn’t put Viagra in the water!

I currently have a lot of cucumbers in that same fridge. Some have been there for weeks and are floppy but some are nice and fresh. If I were to put one of each in the freezer overnight upon defrosting the rigid one would largely turn to liquid because it’s thin cell walls are broken and the water will escape, it’ll be a mess. However, the soggy one will be in a slightly better state and this is the salient point because, at the outset there was less pressure on the cell walls which allowed for the expansion, less damage was done and less water is lost and we can make some nasty soggy sandwiches with it.

Frozen water (ice) is dry….obviously. It’s why your freezer keeps food good for years on end because where there is no water bacteria cannot ply its trade. Our Alpine mugo pine survives months without water over the harsh frozen winter but how? In very severe cold climates native trees remove water from their cells, tolerating the dehydration of the cell contents, and place the water between the cells where it can freeze without causing damage. This works where the weather provides a prolonged slow descent into extreme cold.

Larch roots desiccate in winter and should we be poking around down there too early it the season they appear dead, just a black outer membrane and a thread down the middle. However all is well because come favourable conditions the root will reinflate itself and carry on as before. It’s a protection measure to prevent roots from freezing damage. Bear in mind larch grow very well with wet feet in damp places where simply shedding water is not possible. Most plant species and tree species in particular have what often seem fantastical winter (or summer) survival strategies to deal with extremes of climate.

From the above it’s obvious we may need to consider the effects of water in relation to overwintering our bonsai trees. In some instances we may need to take some practical measures but as always consider your actions carefully and go steady.

Temperature is another factor that can have a significant effect on trees in almost every aspect of their existence as we saw earlier. Thankfully here in GB we don’t see those extremes. I say that because I believe the British media are a bunch of tossers (by and large) we do not have extremes. We have what’s called a temperate climate ie: those without extremes of temperature and precipitation. The changes between summer and winter here are invigorating without being frustratingly extreme. There are two types of temperate climate: maritime and continental. The maritime climate is strongly influenced by the oceans, which maintain fairly steady temperatures across the seasons. Since the prevailing winds are westerly in the temperate zones, the western edge of continents in these areas experience the maritime climate. Such regions include western Europe, in particular the UK, and western North America.

I won’t be delving into the intricacies of that particular aspect as it’s not really a concern for us. However do bear in mind not all trees or their multitude of species and sub-species are the same and so knowing what you have and understanding its natural range is important. As an example take the genus Acer this contains the varieties ginnala (Amur maple) and buergerianum (Trident maple). The former can withstand temperatures down to -45C whereas the trident will be dead around -6C. So, know your plants.

We can see, thus far, that getting our precious bonsai trees through an unpredictable British winter is always going to be a bit of a weather based crap shoot. Earlier I remarked that a bonsai tree is a tree largely cultivated in a very un-natural situation and very often a very long way from it’s natural environment. Our mugo for example is a fish out of water here in soggy GB. However plants are tough and adaptable which is why we get away with what we do.

Bonsai are never going to have a large enough root system to really thrive. Anyone who has grow material in the ground will know how fast a tree can bulk up once established. Compared to pot cultivation the development rate can be 10x faster. Mother earth knows how to take care of her trees. I also wrote here years ago about how capillary action turns a shallow pot into a puddle in winter. Also bear in mind a tree with its roots in the ground enjoys a fairly stable temperature. In winter even if the surface is frozen solid, just a little below the surface it’s +4°C. A bonsai trees roots will be almost the same temperature as the ambient air. Plants in the ground don’t typically see more than a few degrees of temperature change whereas a bonsai could easily see a 20 or 30 degree swing in as little as 12 hours, particularly in summer or during a cold snap. That’s unnatural and a tree like trident maple will not cope but then our mugo pine is going to be just as vulnerable because at the altitude where they occur naturally in never gets warm, even in summer. A pot sitting in direct sun in summer can easily hit 40°C or more. Ever seen one steaming when you water in the early evening?

Having set out in brief (???) some of the more significant points concerning the survival of bonsai trees over winter please allow me the indulgence of expressing some personal opinions and observations. Because we are clever bastards we can grow trees in little pots, many are tough enough to stick two fingers up at us and carry on regardless but some are not.

Most of the bonsai trees that end up dead are not the result of weather, disease or pests. Dead bonsai are almost always killed by their owners though likely not on purpose. Nowadays we refer to that as abuse, a widely used and abused term. Abuse is when someone causes harm or distress. It can take many forms, ranging from disrespect to causing someone physical or mental pain but in this case most often it’s a case of neglect and ignorance.

In bonsai we can define the term as not providing the appropriate conditions and materials for our charge to thrive and survive. Like a customer of ours from years ago who spent a lot on a stunning tropical variety of bonsai and insisted in keeping it inside his log burner (the doors were open) all year. It looked nice apparently but as I warned him that wouldn’t last long and it didn’t. It never ceases to amaze me how newbies know so much more about bonsai than those of us who have spent our lives learning. Ya’ can’t educate pork!

In order to get a bonsai tree through the winter in tip-top condition it’s important that it’s in tip top condition long before the winter even starts. In my experience (we buy a lot of bonsai collections) the larger part of trees called bonsai in this country are no more than a harsh winter or two from the compost heap and so when adverse conditions come along, way too many are left with little defence. Kind of how many folk are just one or two pay checks away from financial oblivion.

I write here ENDLESSLY about inappropriate re-potting of bonsai trees and that’s a VERY significant reason why so many trees die over winter, they just never get to build a mature root system or reach a stable equilibrium.

Case in point, back in 2019 I recounted The Tale of Two Maples. It’s interesting to look back and that sorry little deshojo featured, it’s still with me, just compare these pictures taken four years apart at the same time of year. Which do you think will stand the best chance of surviving the winter?

Deshjo Maple Bonsai in a poor state

Deshojo maple bonsai September 2019. Not looking good.

Deshojo maple bonsai tree, How To Stop Killing Bonsai Trees - Thoughts On Winter Care

Deshojo maple bonsai tree. September 2023. Hale and hearty. This will go through a tough winter safely.

It’s a long story for another time but illustrates my point, we need to work hard, sometimes by not doing things, to ensure our trees are supremely healthy at all times. That way they are going to shrug off adverse conditions much more readily than not. Only a fool would expect a pint swilling, pie eating 40-a-day sofa spud to go run a marathon successfully. That’s got disaster written all over it. But, a poorly bonsai tree in an inappropriate pot, the wrong soil structure, badly situated in the garden that’s been badly pruned to the point of weakness and poisoned with inappropriate use of fertilisers, pesticides and fungicides does not come through a bad or unpredictable winter and everyone goes looking for some exotic disease or similarly lame reason to excuse their own long term failure. Others, and I have heard this a thousand times tend towards the “it just died, I don’t know what happened, it’s been fine for years” type of platitude.

I’m yet to see, or hear, of any tree that committed suicide. Given appropriate conditions trees don’t die wether they are in a pot or their natural environment. Where a tree in nature does die it’s because things have changed, trees have grown up around it, successive dry or wet seasons excess or lack of sunlight or nutrient poverty. There’s always a reason but much like our dead bonsai trees after a rough winter it’s not always obvious even though everything we need to know is right there. Trouble is once the piece of paper with the verdict is handed over 9 times out of 10 it’s got our name on it hence …… How To Stop Killing Bonsai Trees – Thoughts On Winter Care

If you have managed to read this far I’m betting your head’s going ding-dong about now so by way of a little light relief lets look at some practical examples based on my experience. There can’t be many of us that have not or do not have trident maples. Now I already touched upon their being particularly susceptible to freezing. This year I lost count of the folk calling me for advice on the variety so what typically happens?

Tridents, much like Chinese elm are really warm weather trees. They grow at least 6x faster in a greenhouse than they do outside in my garden. In the winter, assuming the soil is very dry they will be okay down to about -5°C but if their soil is really wet or waterlogged, which is almost always the case outside, they won’t. A combination of thick fleshy root structure, the soil we tend to use for thirsty deciduous bonsai, shallow pots and pretty moss coverings to the soil surface all mean a tree sitting outside under the sky is likely to end up very soggy. When this freezes hard the roots, other than thick lignified parts, are quickly lost due to excess internal water expansion and hydraulic pressure from outside. Just try adding an additional 10% of soil into an already full pot, hydraulic pressure caused by expansion of freezing water is easily sufficient to bust open even the largest and strongest ceramic pot. Just think what it’s doing to soft tender roots.

Now assuming this maple was going great guns all summer and shut down correctly in autumn it will have stored a lot of energy in it’s woody structures. Come spring time the tree will leaf out like normal but then growth will slow really quickly, leaves may be normal to begin but as a shoot develops the size rapidly decreases before typically the end of the shoot stops, may droop, discolour and eventually dry out altogether. Other leaves are lacklusture and will quickly discolour, curl up, or down and all activity quickly ceases. At this point most folk start thinking about ‘feed’. That’s a bullshit expression as I have said before, you can’t feed a plant but enough of semantics.

What’s happened in this example is that the tree has stored it’s previous seasons energy like a battery. At the appropriate time this has fired up and got the motor running. Trouble is over winter some little bastard came in and syphoned off the tank so there’s nothing behind the battery to really kick up the activity after the starter got us running so progress quickly stalls. The tree remembered it had a root system so chucked out an appropriate amount or new growth which quickly collapses because the frost took the roots away. Because most or all of the roots are gone the water column collapses, foliage cannot be supported and most times the tree will eventually die completely though, typically it’ll linger until well into the second half of summer, teasing you all the way.

At this juncture some bright spark’s going to ask what’s the difference between a tree that’s had it’s roots nicked by frost versus one that’s had them all chopped off in an overly enthusiastic re-pot. Trust me there’s all the difference in the world but my heads now getting too tired to explain. Health, vigour, timing and new soil all have a part to play

Sometimes a bonsai tree in this condition can be saved but it’s not an exact science. As discussed, a supremely healthy tree has significantly better odds. What has worked for me, and others I have shared this with is as follows. Keep under cover protected from rain exposed to as much sun as is possible and out of the wind. Assuming there are leaves do not mist, spray or foliar feed, we’re on battery power here. Keep the soil dry, if there is moss remove it entirely so you can see the actual soil. A small weed or two is helpful. When the weed wilts flat onto the soil you know the moisture level is about right. The most critical element of this is that soil moisture level and maintaining it right on the edge of almost too dry.

What we are doing here in effect is rooting a big cutting and if luck is on our side and damage is not too extensive it will work. The combination of a little stored energy and some small input from the leaves might just be sufficient to fire off a few small feeder roots which in time will develop sufficiently to restore the water column. Think of Bear Grylls making a fire from a spark. A tiny fleck of dry tinder smoking lightly, with care develops into an ember that’s slowly cultivated into a tiny flame and so on. Once new extension growth, which should be left to aid recovery, is romping away at one or two feet long we can begin the application of a tiny amount of fertiliser. Once you have seen good autumn colour and a text book leaf drop, breath a sigh of relief.

Bearing in mind what I said earlier about the effects of light and temperature on preparedness for winter. Where trees are grown in a greenhouse or polytunnel it’s fair to expect much faster development than is possible outside in most parts of our country. My advice is come mid-August move deciduous trees outside into full sun and an exposed position. This will ensure the tree shuts down for winter in the appropriate way and time frame. Where trees like trident are concerned I would move then back inside after a couple of light air frosts. Good air circulation and soil moisture management will ensure the tree emerges from winter as fit as a butchers dog. Where trees are put inside for the winter but not intended for greenhouse cultivation in summer move them outside by the end of winter. Don’t worry about light air frosts but if temperatures are likely to drop more than -2C you’ll have to hump ‘em back in for a while.

Evergreen trees used for bonsai that are particularly susceptible to British winters include yews (taxus), Mediterranean broadleaves like olive and Holm/Barbary oaks and Japanese black pines. Yew will do best if it’s soil is bone dry over winter. Yews hate wet feet at any time of year and whilst they may tolerate a wet winter it’s just a matter of time before Phytophora (The Plant Destroyer), a genus of water borne moulds finds just the right opportunity to kill your beloved tree stone dead in just a few weeks. Water really is the enemy of overwintering bonsai in Blighty, significantly more-so than the cold. I know folk will kick at that because their yews have been outside for decades. However just look at the losses this year country-wide. I lost yews like that decades ago but since adopting the above action, and late summer re-potting i have not lost a single leaf from a taxus over winter.

Where pines are concerned things are much the same. Most varieties of pine have relatively poor root systems and the tree relies heavily on it’s interaction with mycelium, a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. This collects water and nutrients which it passes onto the tree in exchange for sugars from the leaves. If this fungi is in poor condition pines quickly become weak with poor foliage colour and reduced growth. Mycelium seems to hate wet conditions, particularly when water freezes in its direct contact. One of the reasons coarse soil mixes are recommended for pines is that drainage is good which promotes development of mycelium as well as allowing large volumes of space between particles for the fungus to occupy. Mycelium allows trees to colonise areas that really do not have enough water or nutrient to support them without the interaction.

To keep a pine tree happy just make sure the conditions are ideal for it’s supporting mycelium and all will be well. This, once again means managing soil moisture over the winter but with the added complication of finding enough light. I’m reminded of the time a few years ago that I came by the most incredible 5 trunk kabudachi Japanese white pine. A massive mature 5 trunk bonsai tree and the best of it’s kind I have ever seen in GB. This came as a PX from a customer in the central belt of Scotland. It arrived here and instantly I could see it was not happy, it was yellow. Being September I was aware there was little time to correct this before the cold arrived. The tree was also covered in algae and lichen, it had obviously been too wet for much too long, not an uncommon problem in that part of the world.

To remedy the problem I immediately set it up in the centre of the polytunnel where the through-draft was significant. I then put a large growlight directly over it’s apex set to run 3 hours either side of dawn/dark to extend it’s day length. After the moss was stripped and I got rid of the lichen and algae I crossed my fingers and waited. By early December, with not a drop of water for over 10 weeks the tree was a pristine blue and the mycelium was growing out of the pot. I then dispensed with the light and it went through the winter perfectly and the yellow never returned, I never did re-pot it or change the soil. Old bonsai need careful and intelligent management if they are to live their best lives.

Finally please allow me to make some observations about spring. Back when I started all this malarkey decades ago spring time was end of march to early June. The Met’ office conveniently dissects the year into four quarters based on the typical weather which as we have seen is much less important to plants than is the daylight. The fact some feckless weather presenter tells you it’s spring because of the date does not make it so from the point of view of your precious bonsai. I wrote at great length about this and it’s relation to repotting bonsai previously When To Re-pot Bonsai Trees. It’s spring when a particular tree begins to grow, not just swell buds but open out and grow. This is one of the most valuable lessons I have learned in well over thirty years of fanatical bonsai work.

This last year really did test this notion for me. We like the idea of seasons and a nice defined difference between them all but, living in Blighty that’s just not possible. August 2020 saw us endure single figure temperatures below +5°C and this year whilst most folk were sweltering in a mini June heatwave here on the east coast temperatures were more like early April thanks to biting cold northeasterly onshore winds. I dare say many of you have similar tales of the place you call home.

So based on my own advice my collection of big old Chinese elms were pushing genuine leaf come mid-March and this was really happening fast probably down to a surfeit of energy from the previous, amazing summer. I got a bit caught up in the moment with uncharacteristic enthusiasm and got my re-potting done. However I should have listened to my typically negative inner voice but wishful thinking got the better of me. March is not largely ‘plant spring’ even if it is meteorological spring and I ought to know better at my age. Talk about pissing on your chips!

What happened next was that the temperatures dropped. February is normally not so bad here if the wind does not come from the north or east and this brings things on quickly. That almost never lasts and cold’s never far away. So this year by end of March it was colder than it had been at any point over the winter and it did not warm up to an appreciable degree (by which I mean steady night time temperatures of +12C or above) until the third week of June. So my elms were getting ready to go in March when I foolishly cut their root systems back by 60-80% and then almost immediately we got back down to low single figures by day and frosts at night, new roots didn’t grow and sap froze solid.

What I managed to achieve was a great success in bringing my elms through the winter only to inflict the damage of a harsh winter upon them in my silly enthusiasm and blind hope of a nice summer. Thankfully nothing was lost though none of the trees made growth worth a damn. I lost an entire seasons development which if you know Chinese elm you will know that’s quite a loss. By comparison I bought in a couple of big monster elms in the spring which were not repotted and they have grown about 2-3 feet alongside mine which have made 3” at best.

This whole subject is so full of ifs and buts it’s impossible to give precise advice on what to do for the best. It’s important to keep our whits about us, look at the bigger picture and not just rely on what may have worked for years on end. Overall the best plan is to have extremely healthy bonsai. If your tree does less now than it used too or shows any signs of distress or slowing down, like poor growth, early leaf drop, naff colour or not drawing water from the soil strongly beware. Remember water is more an enemy than cold and never, for a minute, trust the weather. Keep in place a good care regimen of appropriate watering and fertilising (with a season appropriate product) across the growing season. Keep your tree in an appropriate place based on its natural habitat and only water once soil begins to dry out. The constant drying and wetting of bonsai soil is a key element in our success, excess wet is often a very significant part of failure. Most trees roots require moisture but not water and keeping that constant is our challenge.

This subject is broad and deep and I feel I have barely completed an introduction here. Accept my apologies if I have missed anything, i’m doing my best. However after 2 days writing my head is fried and I have other things to do but hopefully this has been a help in casting a light on what happens when we get a bad winter. The takeaway is this….. Trees don’t die, most of the time they are killed by our ham-fisted oafishness and misguided well meaning ‘care‘. Sometimes it takes us a few years to kill our bonsai. Bonsai requires constant vigilance, understanding and effort and a relentless dedication to our own education. It’s not about having the latest ’snake oil’ wonder product or some special soil mixture or ingredient. Success in bonsai is about knowledge and experience and care, it’s about effort, hard work and dedication, often to the exclusion of almost everything else. If you have to stop your bonsai activity to go eat success is going to be a challenge.

Please feel free to comment or contact me by email if this has raised questions and i’ll do my best to respond. If you did manage to read all of this then I salute you. Sadly i’m fresh out of medals but you deserve one 😉 Thank for your time and support, please share!


Defoliation – What You Need To Know

There are many mysterious techniques used in the world of bonsai tree creation and maintenance. In my experience, many of them are misunderstood and therefore incorrectly applied. In my own case it certainly took a long time to understand what defoliation of deciduous trees was all about. Over the last few years we have been so busy it’s been hard to find time for elective techniques. Thankfully life has settled down a bit of late and I’m back on the tools so here’s Defoliation – What You Need To Know.

Defoliation is the act of removing leaves from a tree. In this context we are considering the near total removal of leaves from a broadleaf tree as opposed to partial defoliation that is a technique used to balance vigour. Back in the mists of time I was under the impression that defoliation was a method of achieving smaller leaves (which ultimately it is). That’s what I was told and also what I read. However I was also told all I had to do was cut the leaves off in early summer. Like most everything in life it’s much more involved than that.

So, here’s what I have picked up along the way…..

Defoliation is a three stage technique that is employed to increase the ramification of broadleaf bonsai trees.

Defoliation is a technique that is performed during the peak growing period of summer. In the UK that is typically from late May to early July depending upon local conditions and the unpredictable weather.

Defoliation is a technique that is used in the later stages of bonsai tree development and for refinement and long term maintenance of fully mature bonsai trees.

Just cutting leaves off your tree might well be the definition of the term but it is certainly not the correct application of the whole technique and will return little benefit. I tried this in my early days because those around me said it was what you did to get small leaves. However, in practice I found that when the leaves returned they were much the same as those that came before. Perhaps my, largely, untrained trees were too healthy or too raw to benefit. I was also told that defoliation would weaken my trees if performed too often.

After a couple of years I largely abandoned the whole affair consigning the idea to the bin of spuriousness. Following that, about ten summers came to pass and I found myself extremely unhappy with my ability to build ramification (a subdivision of a complex structure – fine twigging in this case) and refine my broadleaf trees and so began to revisit defoliation.

For a while I reclined upon the old excuse that the British Isles do not have the most suitable climate and so we cannot do what some other folk can with bonsai. That’s largely bullshit, it has since become obvious to me that we need to develop and refine our own techniques to work here. Back in the day it was largely a case of copying what the Japanese were doing and when that didn’t work very well we just blamed the weather and gave up. Lazy bastards!

Creating bonsai trees is all about helping a plant to become EXACTLY what it would in the wild. A mature example in perfect balance with its surroundings and an integral part of the world. We just want that to happen within the confines of a small stature.

A young tree typically grows with great enthusiasm and abandon. It’s little and in ideal conditions has more than enough of everything it needs and grows accordingly. Later on resources are less abundant to the now much larger tree and so growth becomes more refined. This tree will grow what it needs, shed what it does not and makes efficient use of what it has available. That’s how our bonsai should be.

Here is an explanation I have recounted literally thousands of times before. It’s simplistic but true and proven….

If a tree of a given size requires ten square inches (64.5 square cm) of leaf surface to photosynthesis the energy it needs and it only has a couple of buds it’s going to make two really big leaves. If we increase the number of buds tenfold the leaves will inevitably be much smaller. Ultimately the more buds (growing points) the smaller the leaves, or needles. Anyone who has reduced a wild tree for bonsai by chopping it right down to a nub will have seen how this works over a few years, see my elm below.

It’s possible to get small leaves or needles by restricting a trees ability to grow them. This involves withholding resources like water or nutrients etc. I have seen some dastardly devices employed upon this endeavour. Every time the net result is stress for the tree. If a tree needs big leaves it should be allowed to grow them. Small foliage is the result of good quality technique applied over time in a skilled manner. Choking the living shit out of your tree just to please your warped sense of aesthetics is not only stupid but risky and disrespectful. Us old guys can spot the ‘smoke and mirrors’ every time.

Before we employ defoliation it’s important to determine if it’s right for our particular tree and if it’s the correct time. You tree needs to be healthy. It needs to be holding good viable leaf late into the autumn, it needs to be sucking water out of it’s pot vigorously every day it’s in leaf and it needs to be creating back buds all on it’s own. No back buds no bueno. Go back to the start and restore your trees health.

The structure of a typical broadleaf tree consists of what are known as branch orders. Primary branching (1st order, the first thick bits), secondary (2nd order) and tertiary branching (3rd order). That’s a minimum of three zones of decreasing size and increasing twig density. These orders can extend well out into double figures. For our purposes three orders are pretty much a minimum. Our ramification is built on the ends of these branches. If you do not have this level of structure your tree is NOT ready for the application of defoliation. Please excuse the puerile graphic…..

A tree developed sufficiently for defoliation to be of benefit should have it’s new growth stopped early on in the season. Typically new soft extending tips are pinched out. Stronger parts of the tree are stopped at the first pair of true leaves, weaker parts should be allowed to develop a few extra leaves before they are pinched which helps to balance the trees energy.

Next some careful observation will be required. Allow the leaves to fully form and harden. Progressively stop any emerging shoots as above. There comes a point where growth seems to stall. Leaves will be fully mature and hardened off and there will be a period of stasis. This is a stage when leaves are feeding the tree and replacing the energy it took to produce them, it’s important. Eventually movement will be seen as a second bud break begins and that’s when we need to jump in. With experience and an eye on the weather it becomes possible to pre-empt this moment by a few days and that’s the ultimate.

Defoliation: Stage 1

This is pretty simple, cut the leaves off. Simply sever the supporting stem (petiole) with sharp scissors. The remaining stem will dry out and drop off in a week or so. Most varieties will suffer if leaves are pulled off as this will, remove some axillary buds and can even pull tiny strips of bark off some species. In this context removing part of the leaf is not going to work, remove the lot. Working on a tree like elm the tiny round primary leaves on the current seasons extension can be ignored if they are too small to cut.

Start at the top and work down. It’s possible to leave a few leaves if parts of your tree are very weak. Small inner or lower branches may qualify but in general if you are doing this then do it. Half measures will produce poor subsequent results.

Defoliation: Stage 2

Once the leaves are gone it’s time to prune the new growth in order to integrate it into the rest of the trees structure and do your bud selection. This is much the same as you would be doing in autumn or just before spring flush. A simple rule is pruning to two. Three shoots from a single point cause thickening that will become ugly with time. There is no point developing ramification unless it’s structure is correct or it will have to be removed later on. Remember branch orders, one becomes two, becomes four, becomes eight, becomes sixteen. That’s how to build ramification.

Once pruning and bud selection are complete it’s time to break out the wire. At this moment most broadleaves are like putty to bend and will fix in position within as little as two or three weeks. Where it’s required I take opportunity to lay in new growth and correct errant branches that are getting out of place. Use the opportunity to open up spaces to let light into inner structure. This is the moment that really BUILDS a broadleaf tree and ultimately produces genuine quality. Stage 2 is vital!

After this work is complete I like to leave the tree in the greenhouse for at least a week. The added warmth really helps bring on the new flush of foliage. As soon as I see the fat new buds about to open the tree goes back outside into it’s normal spot.

Defoliation: Stage 3

Once our tree flushes new growth I like to let it extend a little. For a mature tree typically 3/4 leaves, more in weaker areas before nipping out the ends. This typically takes a month from leaf removal assuming decent warm weather. I like to let the leaves mature, they are feeding the tree in the strong sunshine we get so little of in Blighty. Typically six to eight weeks after cutting the leaves (normally August) I will reduce the new extensions to one or two nodes whilst also removing a good percentage of larger and low hanging leaves. This opens up the trees structure and lets light inside. Now is also the time to remove that wire. Assuming it was applied correctly the shapes it was holding will be perfectly set. From here on out until leaf fall make sure you have a good fertiliser regimen and plenty of sun. That will ensure a good season next year.

This last stage is a little different from what might normally be described and is a modification required because of our weather. If you are entirely growing inside then pruning can happen earlier, as can later growth flushes. On average GB gets a fraction of the sun some other places do and we need to utilise every single moment to our advantage if we are going to produce decent bonsai trees.

Who said there was noting to do with mature bonsai trees? That’s a lot of work. But, keep that tree healthy and keep this up for two or three years and the results will be astounding. Bonsai is NOT about what we CUT OFF, it’s about what we grow, it’s about what we ADD to a tree. This defoliation technique works wonders.

Some trees do not take well to cultivation in a small pot. For instance I have a very stout little English elm (ulmus procera). Every year it enthusiastically bursts into life full of the joys of spring. I cut back the new shoots after which LITERALLY nothing happens for the rest of the year and the tree typically starts to drop leaves at the end of September.

In this case defoliation in June results in a powerful new flush within a few days. The new flush is strong with powerful extension and good colour alongside some good back budding. The new leaf stays strong and vibrant until it gets significantly cold which in my part of the world is late into November. That is several weeks later than without defoliation which means more photosynthesis and a stronger tree overall. I have seen this happen so many times with different species now. It rather de-bunks the notion that defoliation weakens a tree. Done correctly the opposite is actually true.

Below I have included images of an evergreen oak, quercus ilex. These trees are the ultimate lightweights. This one spends winter in the greenhouse so by spring it’s leaves are in very good condition. Therefore it will not bother making any new ones. In the past it has gone an entire summer without making a single new leaf.

I was scratching my arse wondering how on earth I could develop this as bonsai if it was not going to grow. The answer of course was defoliation. I now cut it’s leaves away in May and the subsequent flush comes in a just a few days of good weather and it’s incredible. 75% of the ramification you can see on this tree has been produced in a single growing season. In fact a lot of Mediterranean broadleaf evergreens are the same. See the pistacia below. Again that ramification has all happened in a single season.

Defoliation works wonders for some more difficult subjects used for bonsai. Acer campestris is a strong tree that grows fantastically here. However I can count on my thumbs the good quality examples I have seen well developed in the last thirty years. The solution is a double defoliation about four weeks after first leaf flush and again just before the height of summer. The bud selection and wiring stages are vitally important. This works a treat with big leaf maples like sycamore (acer pseudoplatanus) too.

Defoliation is not right for every species. In my own experience Hawthorn, Chinese elm, beech, deciduous oaks and a great many small leaf shrubs will return poor results. Even privet will only produce marginal improvements in our mediocre weather. Many varieties require a modified technique to return their best. If in doubt, so long as your tree is strong, give it a go and monitor the results over the following winter.

One note of caution. This has a lot to do with the weather over here. A few years back I had a spectacular native hornbeam booked for a show in September. So, a little later than I hoped I removed all the slightly scruffy leaves. The expectation was to rock up at the show with pristine shiny bright leaves, not so easy on a native hornbeam that late in the season. I did all of the above and then in August the wind turned to the northeast, not good on the east coast. Temperatures for the whole month hovered around low double figures. The result? Not a single leaf grew until the following spring. Showing a tree with no leaves in September makes you look like a rank amateur so it never went along. The moral? Watch the weather and choose your time wisely!

In effect defoliation gives us a whole additional cycle of autumn, a winter rest and a spring flush. That can, with the application of some skill and sensitivity give us two years development in just one. It exploits the natural growth phases of a tree without hurting it, in fact it makes for a stronger happier tree when used wisely.

Ultimately it is exactly as I was told, defoliation produces smaller leaves. Of course it’s possible to entirely ignore the above and just get rid of the leaves and, if you are lucky they will come back smaller but this just might be the result of stress having depleted the plants energy levels. However as with all things in life there is more to it than meets the eye.

Contrary to my earlier thoughts defoliation is NOT an elective process you can use or not. It’s THE fundamental work involved in creating a bonsai tree with broadleaf species. If you are not doing this you are not creating a bonsai tree you are doing topiary. It entirely explains why we see SO many poorly developed broadleaf trees like maples, oaks and elms. Many folk are too bone idle to do the work. Isn’t that like being a footballer who never plays the game? Where I come from that guy’s a bullshitter and, in the words of Forrest Gump “That’s about all I got to say bout that.”


Defoliation – What You Need To Know. It involves cutting off a LOT of leaves

Defoliation - What You Need To Know. Japanese maple upon completion.

Defoliation – What You Need To Know. Japanese maple upon completion.

Defoliation - What You Need To Know. Holm oak prior to leaf removal.

Defoliation – What You Need To Know. Holm oak prior to leaf removal.

Defoliation - What You Need To Know. New leaves just beginning to show.

Defoliation – What You Need To Know. New leaves just beginning to show.

Defoliation - What You Need To Know. My reticent little elm after leaf removal.

Defoliation – What You Need To Know. My reticent little elm after leaf removal.

Defoliation - What You Need To Know. Early days and first defoliation for this little deshojo.

Defoliation – What You Need To Know. Early days and first defoliation for this little deshojo.

Defoliation - What You Need To Know. Pistacia defoliated for the second year.

Defoliation – What You Need To Know. Pistacia defoliated for the second year.

Two branches enter this image from the right. All this ramification developed in a single season.

Two branches enter this image from the right. All this ramification developed in a single season.

English elm after 4 growing seasons from a chopped down totally bare trunk.

Second season of defoliation and ramification building. New buds opening a week after leaf removal.

Missing The Point – Re-potting Bonsai

When you make that first fateful move and obtain a ‘Bonsai tree’ you take the first step on a journey that just might last the rest of your life. It matters little that your first plant is most likely not bonsai at all. Mine was a sycamore seedling I lifted out of leaf litter in the woods on a dog walk and planted in a plastic plant pot. It could be a cheap poor quality ‘bonsai’ you buy in a garden centre, something you are given as a gift or inherit. The quality is perceived and matters little in our ignorant state of the time. To be clear I did not know what a bonsai tree even was (it’s a partly redundant phrase anyway) and had never even heard the phrase. I had never seen a bonsai tree in any form but I always loved trees and figured it would be nice to own a little one.

Some time later I bought a house that came with a ‘Koi pond’, another redundant phrase seeing as koi pretty much live in any pond. Having been an avid fish keeper since winning a goldfish for tossing a ping-pong ball into a bowl at the traveling fare back in the early seventies my new pond was welcome. You don’t spend much time around koi keeping before running into bonsai trees. Most are normally accompanied by shockingly naff attempts at Japanese gardening. Chinese pagodas, concrete Buddahs, deer scarers and so much tawdry, kitsch and tragic gimcrack it’s hard to know wether one should shit or go blind.

So, from the point I knew what a ‘Bonsai Tree’ was it all started to get a bit pear shaped. Ask anybody what ‘bonsai’ means and you will be regaled with the trite platitude about trees in trays / pots etc’. The emphasis is almost entirely on the pot. Surely it’s the ‘tree’ bit we need to focus on? However for the few of us that managed to cut through all the crap and actually get our arms around this thing the word itself is irrelevant. It may have taken me thirty years of dedicated work but I now know I don’t have ‘bonsai trees’ in fact I just have TREES. Plain simple little trees that I keep in various pots (most of which are NOT shallow, or dishes or even ceramic). That thirty years was full and busy! The crazy things I have done have impacted upon everyone close to me for most of their lives, caused me to quit my job, sell everything I ever loved and put me in hospital with life itself hanging by a thread.

I don’t suggest for a minute that, in order to be good at bonsai, everyone must do the same. However this IS a long journey fraught with danger and perils. You would assume that in this ‘Information age’ learning to grow trees and keep them small would be easy. After all just look at the volume of content out there. I always had a passion for learning new things and today what could be simpler. I recently learned to TIG weld, sure I need to practice and work at it but after about an hour I knew what I needed to buy and once it arrived I knew how to set everything up and within minutes I was sticking bits of scrap metal together.

I previously taught myself how to operate a manual metal turning lathe. Another project required knowing how to work with Marmorino (lime plaster). I learned to spray two pack paint, build a sandblaster and repair our cooker. I mastered the arcane electrical systems of British motorcycles and found out how to apply/repair the patina on my pre war truck. There is not a week goes by that I don’t have to learn something new and these days it’s all at my finger tips. What you are staring at now has incredible potential for life enhancement. Of course a modicum of intelligence and common sense are required in order to use this powerful tool. Sadly for lots of people it just leaves them looking like a tool swinging in the breeze.

Just using the word ‘bonsai’ implies that our little trees are something special, something apart or removed from their wild and unfettered relatives. Right there it all went tragically wrong and we didn’t even get to the second word. As soon as the ‘B’ word is applied to a plant folk of lesser experience totally loose their minds and all sense of reality. The word bonsai is a little magnet that attracts so many myths, hearsay, conjecture and in my working class parlance, bullshit that, in the hands of the uninitiated 90% of these little plants are entirely doomed to die a sad and lingering death. Let’s focus on the TREE bit folks!

As a trained horticulturalist and life long gardener and grower it became obvious to me very quickly that a bonsai tree was just a plant in a pot like any other. The interest and unusual appearance is created by some rudimentary shaping and the tree is kept small only by pruning. Returned to the ground any bonsai tree will quickly return to it’s natural state. Like any potted plant with limited resources at it’s disposal a bonsai tree relies upon it’s owner for it’s essential needs. These needs are simple, light, air and water. It really is SO simple that, after thirty years doing this, I am increasingly perplexed and disillusioned at why folk are struggling with such a simple thing. One guess is that so many folk have become entirely removed from nature, the rhythm of the seasons and all the wonders of life outside.

I would suggest the word bonsai ought to indicate the process of making a small tree. The successful result we can just call a tree. That saves a lot of people a lot of confusion. A fabricator might build you some nice iron gates but if you called them a fabrication, and not gates, some people might be confused because the word has several connotations. The word gates is quite specific as is the word tree. In the minds of the un-initiated bonsai is the same.

So, here’s the thing. What’s the big deal with re-potting? 99% of the questions I receive concern re-potting. Before someone buys a tree they want to know when to re-pot. After they buy a tree they want to know when to re-pot. I see people re-potting new trees they just got, re-potting out of season in fact, looks to me like the bonsai community, and I use the term lightly, is totally and utterly obsessed with re-potting to the exclusion of all else.

As a motor-head please allow me a motoring analogy. The last time you bought a car, once you got it home what was the first thing you did? I am betting it was not to go outside and remove the engine right?* Assuming you are the kind of person that could actually do that successfully I would guess that before you did you would check how it ran. Most folk buying a motor would buy a fairly decent one that would do a good job. Some folk like me would seek out the opposite because we like a project but that’s an entirely different thing.

So why on God’s green earth would you buy a bonsai tree and instantly assume it needs to be re-potted? Most bonsai trees are killed by over-work. In my estimation, the number of bonsai trees sold in the UK that survive a ten year period are a single figure percentage. A lot of those die because they are literally pruned to death, weakened as a result. A lot die because of inappropriate horticultural care, like keeping them indoors or in other inappropriate situations. A few are poisoned with fertilisers and other snake oil concoctions. But, the lions share are killed by re-potting.

You would assume this is the exclusive domain of the novice who, on a good day I could excuse for their inexperienced fumblings and daft questions. We all have to kill a few trees, that’s the price of an education. But, sadly this issue seems to afflict even some of those with decades of experience. In that case it’s rare that trees actually end up dead but inappropriate re-potting is responsible for a lot of beautiful old bonsai trees being turned into raw material as they end up with juvenile vigour and lose their maturity.

I assume folk must read that a bonsai tree needs a free-draining soil. Most bonsai trees you buy do not have a free draining soil, at least not in the estimation of many folk who are most likely not experienced enough to make that judgement. Trouble is, if you put a tree into a free draining soil mix how long will that last? Even the most open growing medium will close down after a while simply because it’s pore spaces are filled with pesky root. So you buy a tree and when you water it does not drop right out the bottom of the pot, it must need re-potting right? Perhaps a responsible person has spent several years making sure your new tree has a good strong and vibrant root system. Not always the case but mostly so. Going out and throwing that work away on an ignorant misunderstanding is criminal.

A bonsai tree, just re-potted in the right way, allows water to drop through the soil pretty quickly. However after a year or two that’s not going to be the case simply because the pot is filling with root, as it should be. So, then it takes a little longer to thoroughly wet the rootball when you water. On the other hand it can remain quite wet if it’s raining so then what? I have explained this so many times i just want to go chop my own head off. I have made videos and written dozens of times and explained it in demo’s and a thousand telephone conversations.

Bonsai trees go through phases of development. Initially we are looking for explosive rampant growth in order to build a powerful trunk. Subsequently, we have to build primary branching, secondary branching and finally mature ramification. It is NOT possible to move onto any one of these phases before the proceeding step is complete. Each stage has its own technique too and using the wrong one won’t work. Anyone ever seen a trunk double in size where a tree is planted in a bonsai pot (in the UK)? Not in less than forty years you have not. In order to grow a big trunk you need a lot of growth. In nature a big tree carries a LOT of branching and foliage. I wrote about that at length here  Upside Down Bonsai

That last phase of bonsai development is not understood by many folk. Remember when you were young you had boundless energy and strength to do most anything. Later on in life that started to fade but then you were a little smarter and so managed to compensate and do more with less. That is how we mature a bonsai tree. The whole process and point of ‘bonsai’ is to bring a tree to maturity in order to create a miniature characterisation of the venerable old soldiers that touch our souls. In the early stages we have to tolerate boundless explosive growth but the WHOLE object of the exercise is to bring a tree to a mature and stable place of balance exactly as happens in the trees wild natural home.

Trees in nature follow this path. When young they grow away like weeds exploding in every direction. Later on they become larger, heavy and tall. After decades they will begin to bump up against the law of scarcity. Limited resources in the form of water, sunlight and nutrients coupled with the effects of weather and competition mean that growth has to slow and mature. Rather than making huge straight and soft vulnerable new growth, a tree will begin to create a more robust, long lived and ultimately efficient fine ramification that is very good at what it does and looks beautiful to our eyes.

The law of scarcity or the scarcity principle has two sides, one being that all resources are limited, the other side is that demand is infinite. Limited resources are one half of the fundamental problem of scarcity that has plagued humanity since the beginning of time. The other half of the scarcity problem is unlimited wants and needs. The phrase limited resources means that the quantities of productive resources available are finite. That is what creates those beautiful old and mature trees that inspired us to go out and develop the whole idea of bonsai in the first place. Trees mature once they reach a point at which the resources available to them are no longer sufficient to fuel their infinite demand for increase. At that point a more careful and measured use of those resources means a stable and mature growth pattern that allows for the best return for energy expended.

The problem with bonsai is that most folk are obsessed with re-potting to the point where a tree never manages to mature. Free draining soil, hard pruning, excess fertilisers, too much water and inappropriate positioning will keep a tree young, possibly vigorous and trying it’s best to expand rapidly. That coupled with the owners immaturity, lack of patience and inexperience mean a tree can never truly mature and actually become bonsai. All clever wiring and pruning do is make a tree ‘look’ like bonsai. Actual bonsai is a mature and harmoniously balanced tree that is at one with nature and it’s surroundings and has reached perfect equilibrium based on the law of scarcity. I would call the process of achieving that state ‘bonsai’. The successful net result I would call a TREE.

This all feeds into so much of what goes on in bonsai, most of which is entirely unnatural and ultimately harmful to trees. How many times have you seen a discussion about how to reduce leaf or needle size. A mature and balanced bonsai tree will not have overly large leaves. If it’s mature it will have good dense ramification and a stable root system which interprets as nicely formed leaves. If you are trying to make bonsai from an Indian bean tree (Catalpa) this won’t work but the endeavour was doomed from the start.

If your pine tree grows big needles it’s because it needs them at this stage in it’s life. Inducing stress by doing something dastardly is not going to help, in fact it’s likely to severely upset your tree and retard it’s progress. Young pines have big needles. To get small needles you have to mature the tree and that takes a long time assuming you know what you are doing which many folk do not. Kids have excess energy. Gagging them and stapling them to a wall by their clothes may well arrest the annoying and excessive motions about the house for a while but it will not actually turn them into your venerable grandad. As soon as they get free again it’s probably going to be worse than before.

Real bonsai technique is the art of marshalling natural forces that bear upon a tree to bring it to maturity. As in nature so in bonsai. It’s a finely balanced art form. Mastering this is a lifetimes work. Constant obsession with repotting bonsai, free-draining soil, obsessive fertilising, unrestrained pruning and unnatural meddling is feckin’ stupid, don’t do it. Learn your horticulture folks!


Should I repot this bonsai tree?

This little tree is so far off kilter it’s in mortal danger. Will repotting help?

A mature Chinese elm bonsai tree. Repotting bonsai

This little elm started off like the one above. It took about 6 years to reach this relatively mature and balanced state and only two repots in that time.

*I actually did that, aged 16, I took the engine out of my first motorcycle the day after I bought it. Therefore I do get the re-potting obsession but I was an ignorant impetuous spotty teenager with a dangerously inquisitive mind and a box of spanners.