“Bonsai are compact. The tree always wants to get bigger. Bigger, bigger, bigger (gestures as if the tree is inflating like a balloon). We always work to make our bonsai more compact (gesturing as if the balloon is incrementally deflating). Konpakuto, konpakuto, konpakuto”
Above is a rough quotation from Keichii Fujikawa at the Korean Hornbeam workshop that I’ve talked about several times over the course of my posts. It’s not that the idea of bonsai being compact had eluded me before, nor was his wording (or the approximate translation of it) particularly insightful, but for some reason it all just clicked for me at that moment. What Mr. Fujikawa instilled in me that other sources had not, was the idea that bonsai are constantly changing. Even trees at their pinnacle will not stay that way unless we work diligently to keep them there. The tree is always going to grow according to its nature, which is always bigger and bigger. We, as bonsai trainers, must always work to make the trees ever more compact.
When we talk about making our trees “konpakuto” we’re talking primarily about ramifying the branches. If you’ve done any reading on bonsai or have talked to any bonsai enthusiasts, I’m quite certain you’ve heard the term “ramification” tossed around a lot. When we talk about compacting our trees, we not only mean to make them smaller, but also to make everything about them closer and more neatly packed together. Denser.
You can look at a huge maple in the wild and it will be extremely dense. You may not even be able to see through it. If you were to let your bonsai grow without trimming it would not become dense. Shoots would grow long with leaves every couple of inches. Eventually you would have what looked like an unkempt bush. So why do trees in nature become so dense without anyone to cut them, while our bonsai would look terrible without assistance?
Partly this is due to size. Think about the ratio of the size of a normal tree’s leaves to it’s overall size and then compare that to the same ratio in bonsai. You’ll find that the difference in size is large on the full-size tree in comparison to the bonsai. Basically this means that every leaf on a bonsai occupies a larger percent of the tree’s total canopy than the leaves on a regular tree. The basic nature of a tree will tell it to maximize it’s energy production. The denser the foliage, the less efficient each individual leaf is at producing energy. If the branches grow horizontally faster than vertically, leaves are much more likely to cover up one another and shade out the sun. Simply, leaves and branches in the sun keep growing, while the ones that are shaded eventually die off. If a bonsai were to grow like this naturally, it wouldn’t stay alive very long.
On full scale trees, time and nature shape the canopy; And there is simply more space for branches to grow horizontally and fill in all the gaps. The proportion of leaves that will be shaded out by the canopy is smaller on regular trees because there is just so much space.
This is not the case with Bonsai. In order to create a bonsai with dense branching and very short internodes between leaves, we must prune them. In the words of Ryan Neil (though I’ve heard a similar quote many places) “We take unnatural actions on our bonsai in an effort to make them look natural.” Pruning growth and partial summer defoliation on some trees are the primary ways we go about getting ramified branches and making our trees konpakuto.
When we look at pruning for the purposes of compacting, we can apply the same principles of energy distribution as we did with our initial styling. Only this time, instead of working on the macro level of balancing branch strength throughout our tree, we are going to work on the micro level balancing leafing on our branches. The most important thing to keep in mind is that it’s always preferable to grow a branch from scratch,rather than try to make it bud back. Obviously there will be many situations in which the optimal conditions will not be present and the best use of your material will require that you coax your branches to bud back, but if possible do your best to grow your secondary branches from scratch.
Think of the tree as being a river. At the base, many little creeks feed into the river to make it wider and wider (that’s the roots). As the river goes along it begins to form a delta, where the river splits and splits endlessly into many little creeks (the limbs). If we were standing next to a particularly strong creek and decided to build a dam, one of two things would happen. Either the water would over flow and run around the dam, creating two creeks, or the water would back up to the last split in the creek and be diverted to the other branch of the stream. We can think of a tree’s growth energy in the same way. When we cut off a branch, the energy that was being spent to grow it is no longer necessar; but the tree is still feeding energy to this section as if the branch still existed.
Every tree responds to this a little differently. If we were to cut the branch of a maple, hornbeam, or many other deciduous trees at the trunk; it would soon sprout a couple of branches around the ring of where the branch was cut from. If we were to cut back the leading tip of a branch, the new growth would likely sprout from the base of the leaf stalk closest to the cut. On maple you would get two sprouts because the leaves grow in pairs, while on hornbeam you would likely get one sprout because the leaves grow alone in an alternating pattern. Junipers are a little different because they have a tendency to force new growth either from the other leaf tips or the crotch of two branches meeting. In the future I will post species specific instructions, though there are already some great references for those (check in the Library).
The point is (with very few exceptions) that the key to konpakuto is periodically cutting our trees in a way that forces them to prioritize creating new points of growth, rather than extending already existing growth. We go about this by cutting back the furthest tips of growth located on the very edge of the canopy. Shoots that extend beyond the silhouette of the tree are prime candidates.
Pruning typically begins in the spring. As I’ve said before, there are a few exceptions, but the majority of all major work we do on bonsai takes place in the spring. during this time of year the tree is gearing up for explosive growth. With all it’s energy on the verge of release, the stress of major work can be tolerated without significant drawback. Pruning for the purpose of compacting deals mainly with new growth.
If we’re styling a maple for example, new growth will come in the form of strong shoots emerging for the branch tips. You can always differentiate the new growth because the branch will be bright green, as it hasn’t yet formed bark. As the tree’s leaves emerge in the spring you’ll notice that they are bright green in color and have a texture similar to a latex glove. As the spring progresses into summer the leaves will “harden off”. They will loose their thin latex feeling and will become significantly more stiff. The leaves will also undergo a color change, becoming a darker and deeper green. Once the majority of the tree’s leaves have hardened off, we can begin trimming.
Take a look over your tree and identify the areas of strong growth. These will probably be shoots that have produced 2-3 new sets of leaves since last year’s growth. This shoot length is relatively safe to cut. The danger that exists when cutting new growth is that young branches can have extended die-back when cut. They are so tender that once cut, the sap can run uncontrollably and the loss of osmotic pressure can collapse the channels through which sap flows. Once this happens the branch will typically die back to the bark (last year’s growth) but could progress even further. If you identify new growth that you want to cut, its best to wait for 3 or even 4 sets of leaves before you cut it back. By doing this we maximize the potential growth for the season (by increasing the number of times we can trim growth) and minimize the danger of die-back (by waiting for new growth to semi-harden before cutting).
Pruning of this nature on your trees can be carried out once, twice or even more for each growing season depending on the strength of your tree. A tree’s strength will vary depending on a lot of factors, but you can make a rough estimate based on how quickly and vigorously the shoots grow back. If you see a slowing in growth, or you’re entering the end of summer (early September here in D.C.) you would be wise to lay off the trimming until next spring. Pruning also does not have to be done all at once. For me it works good to trim as the tree grows. It’s not as if i’m cutting 3 specific times over the growning season. Rather I prune the new growth as it reaches a stage at which I can safely cut back to the desired length.
An important note here is that when cutting the finer branches on your tree, you always want to leave a little nub (maybe a centimeter) of branch beyond the place you want the branch to bud back to. Lets say I’ve identified a particular shoot that I want to cut. It’s located near the edge of my overall branch structure and I want to cut it back to A. encourage back budding throughout the larger branch and B. make the branch split. I’ve identified the leaf pair that I will cut back to. In fact, it is the first new pair of leaves for this year. The pair of leaves directly behind it are the last leaves grown by last year’s growth. So when I make the cut, I am going to cut about a centimeter above that first pair. That way the branch has a little room to die back without jeopardizing the leaves that I want to use for the new branches.
Within a week or so of this trimming, buds should emerge from the base of where the leaf stem connects to the branch, and soon two new shoots will be growing out together. Each of these two branches will sprout two leaves for a total of 4 new leaves and your tree has just grown exponentially. Awesome! Even better, after multiple uses of this technique you should start to see some entirely new shoots sprouting off of the old branches. When you combine the strong growth/ weak growth technique with the bud back pruning technique you soon have what we were looking for. Konpakuto!
I really wish I had some photos myself of the techniques in action. Obviously it’s easier to see what’s going on then just to have it explained. However, seeing as how it is currently snowing outside, I will not be able to supply those. The video above is from the Bonsai Art of Japan video series created by Bjorvala Bonsai Studios. I’ve commented before that in my opinion this series is THE video series on bonsai to watch. This installment deals a great deal with the techniques I’ve discussed in this post.