translated from German into English by Michael Eckardt,
Kitchener-Waterloo Bonsai Society
Kitchener, Ontario, Canada
Refurbishing a Japanese maple - the "hedge cutting method"
by Walter Pall
Every bonsai book describes how to work on deciduous trees to obtain the best possible ramification. All books recommend pinching. That means that immediately after the first bud break, the new shoots are pinched back to one or two buds, and that shoots that don’t grow suitably, are removed. The stated goal is to avoid long internodes and to force the tree to produce visibly smaller buds and tinier leaves with its second flush. With that, the tree is said to reach a fine ramification over many years.
Truth be told, a tree is badly weakened by the removal of the early new growth. As a consequence, it can only build weak “starvation” buds, which indeed will grow smaller shoots. This second flush is then clipped off again, and the tree is weakened even more. Eventually, they tree will become so weak that it might die.
According to my observation, this is a very questionable horticultural practice. This method only works to maintain a finished tree for some time. Eventually it will be so weak that one has to bring it back to health by encouraging strong shoot growth. To pinch a tree during its developmental phase is pointless any way.
How is it going to grow, how is it to back bud, if it doesn’t have any strength? I have seen a whole lot of trees that were run down in this way.
How did this misinformation arise? Well, a few decades ago when the first bonsai trees were brought to the West, the purchasers asked how they should care for these trees. The answer was given so that no mistakes could be made. It was assumed that the owners wanted to keep the trees in the state in which they purchased them. The pinching was recommended because it is useful for trees that are ‘finished’ and ready for exhibition or sale. Nobody thought at that time that the Westerners would ever be able to develop bonsai themselves.
In the developmental phase, the goal is clearly to improve the tree. The trunk and the branches must be thickened, pruning wounds must close and the tree is to develop so many new shoots that one has a choice of useful branches. The nebari should also improve significantly. At this stage, the immediate image is secondary to the future beauty. That is why leaves can be large and the tree can look ugly for the longest time. To achieve these goals, the tree needs as much excess energy as possible which it can only obtain through the photosynthetic activity of as many leaves as possible. If exactly those sources of energy are removed too early, then the tree can’t develop. In the worst case, it dies a slow death.
Well, it happens that most of our bonsai are not ‘finished’ trees, but that they are likely in an early state of development and we want to take them further. Even imported tree that look pretty good have to be developed further. Therefore it is important to know the steps to develop trees successfully.
For decades I have been using a method successfully which is pretty much the opposite of the normally recommended approach. You can look at my picture gallery to get an idea if my method works, or if it harms the trees as many people think. All my broadleaved trees - even the most valuable and best known - have been treated this way for decades.
The following example discussing the restoration of a Japanese maple is valid for many broadleaved species. To begin, the tree has to grow as much as possible to have as many leaves as possible that, in turn, develop the energy that ends up in new buds and new growth. If the first flush in spring is allowed to grow freely, then the shoots grow very long. After about six weeks they harden off. The numerous leaves produce lots of energy in the form of carbohydrates that moves downwards through the branches and is deposited in the branches, the trunk, and finally the roots. The result is that branches and trunk thicken, that the surface roots - the nebari - also thicken, and that the roots grow strongly. At the same time, many new visible and dormant buds develop. The entire system “tree” is strengthened and it has good reserves for any setbacks. A radical cutback is such a setback.
In Central European climate about six to eight weeks after the first flush, in our area from the middle of May to the beginning of June, the tree is then cut back with big sheers to its previous silhouette. It is irrelevant where exactly it is being cut, or if any leaves are cut. This actually ought to occur as a partial leave pruning will allow light and air into the crown of the tree. All other growth inside the silhouette is not touched but strengthened with this method. And the tree is strongly encouraged to bud out again. Many dormant buds react to this radical cutback and break, even on old wood. The tree experiences the radical cut back as a trauma and over-reacts because it can mobilize much stored energy. It produces visibly more buds and activates dormant buds than it otherwise would. Exactly like after trimming a hedge. A hedge keeps getting denser if it is cut properly. Excessively long internodes tend to grow at the end of new shoots and they will be cut off with this method. This method, therefore, doesn’t create the feared long internodes. Even the largest leaves grow at the end of the new shoots and are removed completely.
The second growth is then left until early August when it is also cut off completely. The beginning of August is an important time in Central Europe. Any later and the new shoots may not harden off in time for winter. Usually, the tree needs six to eight weeks to the beginning of October to harden off. Afterwards, not much grows. It can lead to big problems for the tree when it is cut after the beginning of August as green branches will not survive the winter.
From the beginning of October to the next March, the crown can be cut again. During its dormancy the tree will not be encouraged to bud out again. When the leaves are off, one can finally see what was produced over the summer. The entire crown has become much denser, and there is much that needs work. Many branch stumps are created that must be removed now. The same with dead branches or parts of branches. But there are so many shoots that one can chose with which to work - the others can be removed completely. Sometimes you even have the problem of having too many branches to chose from. Most of the little branches will be cut back to one bud (opposite budding trees like maples) or two buds (alternate budding trees like hornbeams). In some areas where the crown needs developing less is removed. As a result of this work the tree will look quite beautiful. At this point, you can also recognize which branches should be changed in their position. They can the be wired the traditional way, or moved with the help of guy wires.
In addition to the ‘hedge cutting method’ you can use sacrifice branches in special situations. When a branch or trunk need thickening in comparison to others, just leave a few branches grow during the entire growth period. They can grow to one meter or more. The rest of the tree is treated as described. This way, the branches and the trunk beneath the sacrifice branch will thicken and the nebari will strengthen. This method is especially useful to improve the lower branches that normally don’t thicken because of the apical dominance of most trees. The example tree, however, is just the opposite - it is basally dominant. It’s upper branches are weaker and they are specifically strengthened with sacrifice branches.
Broadleaved trees can be markedly improved when this method is consistently applied over a number of years as the featured maple demonstrates. When it finally is ‘finished’ one can pinch again, especially when it is to be shown at an exhibition. At this point it will be showable for a couple of years - the goal for all bonsai enthusiasts. But eventually, the tree will deteriorate and has to be strengthened again with strong, new growth.
The disadvantage of my method is that the tree can be shown only rarely over many years. There’s always something that isn’t quite right: too many branches, guy wires, a altogether neglected appearance. Temporary beauty is deliberately sacrificed for future quality. But top trees can only be created this way. If you don’t want his, if you are not ready to pay the price for quality, then you have to live with the fact that your trees don’t improve, and even deteriorates over time. But you can enjoy looking at their beauty for some time. And this is exactly the advice we received from Japanese gardeners decades ago.
Picture 1: 2008-05:
The tree arrived in my garden in this state. The previous owner had
kept it in Akadama mush and thought that he would automatically improve the tree by
pinching. The crown is much too wide and flat and the leaves hide poorly structured
branches. Many branches are dead. The Nebari could be much better and the maple is
planted too high in its pot.