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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.”

G.

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!

G.

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.