Base Dressing Fertilisers & Bonsai

Way back when I started bonsai in those halcyon days just before the internet ruined most everything, after I had exhausted my local library, I stumbled into a local bonsai club. This had what might kindly be called a parochial attitude to our hobby. Very traditional in approach, were it not for the lack of impressive produce one could be forgiven for thinking it was a meeting of allotment holders. In fact many folk there were indeed allotment holders, me included eventually.

I remember vividly how entrenched ideas were and anything new, especially from a whipper-snapper like me (yes I was young once) caused much furrowing of collective brows. The debate around Akadama vs John Innes and grit eventually became quite aggravated but the one I loved most was the conflict over chemical vs organic fertilisers.

Back then gardeners had a lot less choice and with an almost complete lack of bonsai tree specific fertilisers our options were minimal. I remember that chicken manure in a dried pellet form was just becoming widely available at the fledgling ‘big sheds’ like the new B&Q mega stores that were popping up all over. Fish/blood & bone was another traditional “organic“, nasty stuff! On the other side of the equation there was Phostrogen, Miracle-gro and Tomorite.

We did have one enlightened individual that introduced me to the use of Rapeseed as fertiliser. This could easily be turned into ‘tea’, pellets or even applied in its raw state. I had seen it’s use in Japanese books but at the time no commercially prepared products were available here and besides I would NOT have been able to afford them.

I instantly understood the value of organics as fertiliser. Not only did they provide nutrients to the tree but they also supported invaluable bacterial and fungal activity within the soil and somehow it made perfect sense to me. Today I use 99% organic fertilisers across my garden wether for bonsai, my wife’s flower garden or veg’ and fruit growing.

I have to say that within our genteel pass-time still those two subjects are contentious. I don’t see the need for so much tribal conflict though. At the end of the day, if it works for you keep at it…. a la salud! Still, it’s in our nature to be tribal and fight and if that’s your thing ‘have at it‘.

At the end of the day it matters little what soil or fertilisers you use for growing bonsai. What matters is how you manage the whole process. Everyone seems to want a free draining ‘soil’ for bonsai but I have had a great deal of success using straight garden soil. One lovely old fellow I met had used nothing else for 30 years and when I got the chance to buy his collection I kept most of it personally because the trees were so good.

The soil bonsai are in matters less than how we manage it. Using sandy garden soil certainly reduces the need for watering in summer but then it does need careful management in a soggy British winter. Fertilisers are the same, included within an intricately structured care regimen most will supply what the plant needs. However….

Managing a bonsai tree is always going to be complicated if we want it to do more than just survive. There are infinite variables to consider and these constantly change. Maintaining optimum growing conditions all the time is impossible but we need to do the best we can. Fortunately most plants used for bonsai are tough and tolerant so that helps us. For instance if a tree gets a bit too much sun during the height of summer it might get a bit scorched but it’ll live.

Ultimately it’s a lot easier to use a modern bonsai soil mix and purpose designed fertilisers than it is to craft our skill of managing a plant and all the complications that come with it. Now I firmly believe refining our horticultural skill to that level has great benefit but it’s not for everyone and not everyone has the prerequisite skills to achieve success. So it’s good that nowadays we have lots of great products to help us out, make our bonsai better and free us up from the slavish devotions of fanatical horticultural discipline.

I came here to introduce the concept of ‘Base Dressing’. That is the process of adding a nutrient rich substance, in our case a prepared fertiliser to soil. This is a common practice in gardening. As I sit here tapping away at my keyboard fanatical gardeners and allotment holders across the country are busy digging in mountains of festering animal poo before the new season gets under way. This is a time honoured ritual and ensures a good crop from a hard worked garden.

So why don’t we use base dressing in bonsai cultivation? I’m sure some folk do but I was always lead to believe that fertiliser and a newly repotted tree should be treated in much the same way as a bathtub full of water and a toaster. As little contact as possible for the good of all concerned but why?

Last year we put out a little booklet containing my thoughts on fertilisers and bonsai cultivation. If you have read it you will know how fertilisers work and how they release nutrients, you will also know the golden rule, never fertilise a plant that’s not actively growing. There’s a lot of that information contained in the multitudes of old posts here if you search the archives, lots more is contained within the articles posted on our web site. I will try to get the booklet text up soon.

Fertilisers release nutrients in different ways. Refined chemicals tend to be a bit like an intravenous injection, they quickly dilute in water and are rapidly absorbed into the plant, often within minutes or a few hours. Organics however rely on fungi and bacteria to break them down and release the nutrients. Some poorly suited organics do both.

I have talked endlessly about reverse osmosis, what is commonly called fertiliser burn. This is when too much nutrient around the roots causes water and nutrients to be drawn out of the plant causing its water column to collapse. This typically manifests as wilting initially followed by browning or dropping leaves. In time twigs and branches can be lost and entire plants can quickly die. To see a similar result try sprinkling cucumber slices in a bowl with salt.

So if the golden rule is don’t feed a tree that’s not actively growing and knowing fertilisers can cause reverse osmosis why would we add fertiliser to the soil of a bonsai tree when repotting, especially as most trees are repotted at the end of the dormant season and therefore not actively growing?

First up bear in mind that a bonsai tree grows (very slowly) in a small amount of soil. Unlike your hanging baskets and grow bags that get composted at the end of the season bonsai trees need to be healthy for many decades. We have a very unique set of circumstances and so the horticulture used for bonsai is entirely different from that used for almost any other container cultivation.

An actively growing bonsai tree can be expected to strip out most of a soils inherent nutrient within a couple of weeks and our constant watering will do little to help. A growing plant needs tiny amounts of nutrient constantly therefore we need to have a drip, drip approach to fertiliser application and that’s easy to set up with organics. It’s not so easy with chemicals, it can be done but it needs constant monitoring.

There are largely two types of folk in bonsai. Those who are in a hurry, typically newbies, who believe they can push their trees to go faster by the copious and repeated application of fertilisers. Secondly we have those who don’t feed much at all, possibly because they believe it’s all ‘snake oil’ or commercial hokum. I once met a guy who only used water from his koi pond believing the nutrients (which grew copious amounts of blanket weed) were all the bonsai needed. After decades this particular theory was entirely disproven after I saw his poorly looking tree collection.

On the other hand I remember when I was landscape gardening I got hold of a large volume of lawn fertiliser/moss killer/weeder. One of those fucking wonder products that turn your crusty old mud patch full of divots and dog piss patches into a snooker table without any effort whatsoever. Used correctly that might be the case (not) however I gave a sack to my dad. Rather than read the instructions he dumped the whole 25kg onto his fairly big lawn in one go. Ten days later the grass had tuned to nasty black slime.

Getting it right with fertilisers is important whichever way you decide to go and base dressing is an important part of that. Modern bonsai soils are almost entirely devoid of nutrient, they are largely made up of processed aggregates which either have no inherent nutrients or the nutrients were destroyed in processing, firing, washing etc’. We like it that way because we gain control. It’s a bit like when I make cornbread. If I don’t get the preparation right when putting everything together what comes out of the oven won’t be right. In that example it’s no good blaming the oven.

Here at KB we spend more time getting soil right than anyone in the country, it’s always been my passion and today we move close to a thousand kilos of mix every day. This goes to folk growing everything from bonsai masterpieces to plants that eat animals and those growing plants in their wardrobes. We know it’s right so long as it’s used right.

What base dressing does is to light up our inert soil mixes. Unlike normal fertilisers those designed for base dressing in bonsai have been carefully crafted to bring maximum vitality and life to soil without excess NPK which can, as mentioned, cause damaging reverse osmosis. Those nutrients are not required in volume during the crucial period after re-potting. However micro nutrients are, particularly as new fine feeder roots emerge and need those nutrients to create new cells and tissue.

Base dressing also fires up the flora and fauna so crucial to building a dynamic ecosystem within our little pots. Continuing with my cooking analogy base dressing products for bonsai put the heat in the oven. No matter how careful we are in creating a good bonsai soil mix, without the fungi and bacteria required we’ll not be ‘cooking’ and nobody wants to eat raw cornbread batter.

I think part of the problem is where a base dressing product is referred to as a fertiliser which causes the confusion about not feeding newly repotted trees. Over the past several years I have been using base dressing products for all my repotted trees. It’s something I now consider essential at every repot across all the species I keep including deciduous and coniferous varieties. We now carry two primary products for base dressing and my extensive use of both has moved my bonsai forward significantly.

Green Dream™ Soil Source Natural Micro-Biological Soil Additive

There is an extensive explanation of this products use and benefits on the product description page of our web site (click text above for link).

Green Dream™ Soil Source Natural Micro-Biological Soil Additive

Green Dream™ Soil Source is a product that we have developed over the last few years. This is a groundbreaking microbial soil additive product unlike anything else available that is simply added to your chosen soil mix or growing media at repotting time. The product, which on the face of it looks like our Green Dream Original product (small dry crumbs), is packed with beneficial micro-organisms like Trichoderma harzianum which are very well documented as being supremely beneficial to the cultivation of plants and the development of roots in horticulture.

Over several years we added this unique new product to well in excess of four hundred repotted plants at various stages of bonsai development. The results were surprising to say the least. Every plant has thrived, regardless of the growing media or species involved, every plant started growing much earlier than normal and much more strongly and once good growth was underway we noticed a significant improvement in the plants uptake of nutrients from fertilizers with improved growth rate, foliage colour and robust appearance. Over the summer period we also saw a dramatic reduction in problems with pest and disease reducing our use of chemical sprays by over 75%.

Biogold Classic Motohi Premium Organic Bonsai Base Dressing Fertiliser

The original fertiliser from the renowned Japanese BioGold range. There is an extensive explanation of this products use and benefits on the product description page of our web site (click text above for link).

Biogold Classic Motohi Premium Organic Bonsai Base Dressing Fertiliser

“The origins of Bio Gold date back to around 1970. Toshio Tsubaki, a doctor of agriculture who was heavily involved in the product’s development, had been researching microorganisms related to plant growth for over 10 years. However, the discovery of effective microorganisms did not go as expected, and during the days of struggle, he met Kazuo Yamaguchi (then Professor Emeritus at Ibaraki University), an authority on applied microbiology, through a book.

From there, the two began joint research, and in 1983, they finally discovered the bacteria (microorganisms) that became the source of Bio Gold. It was a product that allowed plants and soil microorganisms to draw out each other’s strengths, improving the soil environment and promoting strong plant growth. Bio Gold was developed to take advantage of the functions of these microorganisms and make it easy for anyone to use.

The natural activator that would become Bio Gold was born. This product was later improved and evolved into “Classic Base Fertilizer” and “Bio Gold Vital.”  First released 1986 and in continual production ever since.

This is a solid, organic, slow release base dressing fertiliser. Ideal in autumn and at the time of repotting all bonsai. It creates and nourishes vital roots which are very important for plant growth. Because it is carefully matured over time, using a unique fermentation method, there is no need to worry about damaging plant roots.

Besides the above it’s also possible to add products to your soil mix that are not referred to as fertilisers but contain high levels of nutrient that takes longer to release. These provide a base level of nutrition, often for several months. This is a very useful technique, particularly when dealing with poorly trees. My own personal favourite is….

Green Dream™ – Seaweed Meal – Soil Conditioner & Fertiliser

Green Dream™ – Seaweed Meal – Soil Conditioner & Fertiliser

100% pure sustainable dried British seaweed meal (ascophyllum nodosum). A natural organic plant feed and soil conditioner packed with nutrients. Safely encourages and sustains growth and vitality in all plants from seedlings to ancient trees. Improves pest resistance, soil bio-activity, fertility, water and nutrient holding capacity. Broad spectrum nutrients that are released to the plant slowly over a whole growing season.

To Sum Up…

Personally I highly recommend base dressing when repotting bonsai. It’s something I now do as a matter of course for all my trees. A good modern soil mix with organic base dressing coupled with the use of quality organic fertilisers throughout the growing season and careful watering is a combination that’s hard to beat.

When you grow bonsai in a crappy climate like the one we have to endure here in GB every little advantage must be sought out in order to get the best results and base dressing is an oft overlooked, proven and time honoured technique that needs to be universally adopted. Give base dressing a go this repotting season!

Graham Potter