Irrespective of the growing technique you opt, the main aim of pruning a tree is always to have a control over its growth by administering the development of its leaves, branches as well as its fruits at a later stage. The development of fruits can be managed by thinning out. In fact, this is the main reason why pruning remains a vital aspect all through a bonsai tree's life. Like in the case of trees that bear fruits, it is essential for us to differentiate between pruning to give the tree the desired shape and the tree's care and maintenance. There are special and separate equipment for successfully undertaking both these delicate operations.
Equipment required for pruning the leaves and roots of bonsai trees to give them an aesthetic look includes a set of well designed and sharp scissors or clippers. In the case of the branches, you should always use a pair of well-built cutters. Occasionally, especially in the case of older branches, you may require a pruning saw.
It is important to note that two types of scissors are available for pruning bonsai trees. One of these comes with well-built, large and thick blades alongside broad handles. The second type of scissors has small blades with extended and straight handles. While the first type is used for cutting the leaves the second is employed for nipping the buds of bonsai.
The quality of any bonsai will largely depend on how you prune it to shape. If the trees have been propagated from seeds, you need to undertake pruning quite early. You should do the same for trees grown vegetatively, for instance from grafting, cuttings or layering. On the other hand, you can prune the trees obtained from the wild at a later stage.
One of the fundamental rules of pruning bonsai for shape is to always removing of either one of the two opposing branches on the trunk. This is in keeping with the bonsai tradition, which recommends having alternate branches on the trunk. Apart from this basic rule, bonsai trees are pruned to keep it in your desired shape. However, you should be judicious about cutting back the branches, as when you remove a branch from the trunk, it will not grow again, thereby often resulting in a badly-shaped or asymmetrical tree. Although you can possibly rectify a wrong judgement by means of grafting or having a replacement branch, removing a branch is essentially a very delicate operation and there is no guarantee that you will be successful always. While there are some specific rules, for instance methodical nip the tips with a view to get an excellently branched crown, usually this kind of pruning is something related to the common sense of the bonsai cultivator.
At the same time, it is always essential to remove all suckers growing at the base of a broom-shaped bonsai tree's trunk. In addition, if you want to give your bonsai tree a bush-like shape, it is also essential to prune the main shoot of the tree. In fact, you should be able to select the appropriate branch that you think should develop as the main shoot. All cuts that you make should be neat with a view to help the tree to heal rapidly. Often this means that you will require using a pair of cutters that have somewhat curved blades. To cut branches that are slightly thicker, you should make a small hole in trunk and plug it with grafting mastic to facilitate and speed up the healing process. In addition, it will also help to get rid of all signs of scars in places where the bark on the trunk has grown back. If you have used a pruning saw to remove any branch, it is absolutely necessary to tidy the cut using the grafting knife's blade or a pair of cutters.
Always ensure that the tools you use for pruning your bonsai trees should remain clean and sharp all the time. Make sure that you sterilize the blades of the scissors and cutters with a flame after using them every time. When you do this, it helps in diminishing the chances of spreading viral diseases from one tree to another.
It is worth emphasizing here that you need to ensure that you always use quality tools for pruning your bonsai trees. While the conventional Japanese bonsai pruning tools do not come cheap, they are certainly perfect for meeting all your requirements of growing bonsai trees.
This process is equally important as pruning a bonsai for giving it a desired shape, because it also routinely contributes to the sweat of developing a bonsai of a specific fashion.
However, maintenance pruning differs, as you may prune a tree many times during the period of its growth. In fact, there are many pruning techniques that are dissimilar, each suitable for particular tree species and cultivars. Hence, it is important that you opt for the right maintenance pruning technique that is most suitable for your bonsai tree.
Generally speaking, pruning a bonsai tree for care and maintenance aims at restricting any asymmetrical growth caused by the natural development of any normal tree. In fact, such pruning aims at encouraging synchronization between the branch and trunk of the trees and their foliage. This is necessary for obtaining a tree that can truly be called a bonsai. Pruning a tree for care as well as maintenance is undertaken several times in all through the growing season of the bonsai trees with a view to diminish the number of their new branches by means of disbudding as also to reduce the leaves size by sprucing them. It is also undertaken to keep the shoots short by inhibiting their growth. Precisely speaking, this is a hint of the amount of care required by a bonsai tree for the major part of the year.
This particular pruning technique is only meant for deciduous trees. It involves pinching out the buds using your fingernails as soon as the growth emerges. Normally, debudding is undertaken at the onset of spring. However, it may be undertaken several times and throughout the year on specific trees, for instance maple, elm and hornbeam. If this type of pruning is undertaken over and over again on the same tree, it will result in production of smaller leaves. Debudding may also affect a tree somewhat and, hence, it is important that you feed the tree frequently with reasonable amounts of fertilizers.
This particular pruning process is mainly carried out on trees having broad leaves, for instance oaks and chestnuts. This process involves clipping the leaves down by half their original size during the later part of spring. When you clip the leaves in this manner, they will drop on the ground and smaller leaves will replace them during the summer. You can heavily prune the small leaves of deciduous trees. This means removing their leaves completely. You can trim the leaves several times during the trees' growing season. Trimming leaves is considered to be a radical practice and, hence, it should only be undertaken when the bonsai tree is healthy and robust.
PINCHING OR CUTTING BACK SHOOTS
This pruning process is considered to be the vital maintenance operation on any bonsai tree, as the quality of the bonsai tree's foliage depends on such pruning to a great extent. When you pinch back the shoots, it helps in maintaining the shape of the tree by holding back the natural energy of the tree for growth. In fact, this pruning method may vary from one cultivar or species to another, subject to whether your tree is deciduous or a coniferous.
PINCHING BACK DECIDUOUS TREES
The frequency of undertaking this maintenance pruning method largely depends on the bonsai tree's growth rhythm. In the case of a maple tree, you can repeat this technique several times in a growing season. On the other hand, you may require pinching back the buds of a hawthorn just twice in a season - once in the beginning of summer and again in early autumn.
The technique involved in pinching back deciduous trees is more or less same for all tree species. It involves nipping the shoots just a little higher than the leaf joint, ensuring that you always leave one pair of leaves on each branch. Undertaking this operation will enable the branch to divide and spread out. Simultaneously, this operation will make the new leaves dwarfed. Expert bonsai growers also recommend the use of this maintenance pruning of bonsai trees to promote the sap circulation, which necessarily depends on the needs of the branches. It is worth mentioning here that you should never clip or prune flowering and fruit-bearing trees till they have completed flowering and/ or fruiting for the season.
After cutting the leaves, you should always collect them. This is because if you allow the cut leaves to remain strewn around, it will make your bonsai look untidy. At the same time, these leaves will decompose and will keep the soil moist, thereby favouring infections and fungal diseases.
PINCHING BACK CONIFERS
The aim of this maintenance pruning is same as that undertaken for deciduous trees, however, the technique is significantly different. To begin with, pinching back conifers is undertaken only once in a year, usually during mid-spring, at a time when the young shoots just begin to sprout. In nearly all instances, it is enough to do away with about one-third of the shoots using your fingers.
You can undertake this operation by lightly pulling the shoots and they will come away without any difficulty. Never use scissors while pinching back conifer shoots, as you may run the risk of cutting away the ends of the left over needles, which may then turn yellow some weeks later. While it is important to pull the pine shoots just lightly, in the case of a spruce, you also need to twist the shoots. Different from other conifer species, you should pinch a juniper right back all through the plant's growing season. Usually, the growing season of a juniper begins in mid-spring and continues till mid-autumn.