A bonsai must be pruned regularly. Pruning bonsai is the most important measure for shaping a bonsai and maintaining its shape. Accordingly, the pruning of a bonsai is divided into 2 types of pruning: The topiary (= structural pruning, design pruning) and the maintenance pruning. Both types are important to bring the bonsai into a desired shape and to maintain this shape in the long term.
Why do you have to prune the bonsai at all?
At this question many will shake their heads and think: So that it does not grow too big. This answer is not wrong, of course. But it is only part of the answer.
Why is it necessary to prune a bonsai ?
Through topiary (structural pruning, design pruning), the bonsai is brought into a desired shape structurally and stylistically. Its quality is fundamentally changed and improved from an aesthetic point of view. Topiary is more radical than maintenance pruning and requires more knowledge and preparation.
Topiary is performed mainly at the beginning of the development of a bonsai. In this way, an initial plant (prebonsai) first becomes a bonsai, or an existing bonsai is completely reworked and thus its shape is greatly changed.
Conservation pruning (or maintenance pruning) aims to maintain the given style of a bonsai and to improve the existing form qualitatively in many small steps. Bonsai pruning is usually understood as maintenance pruning. It is less drastic and must be done regularly (about 2-3 times a year for deciduous trees such as maple, apple tree, Chinese privet, ficus, hornbeam, June snow, linden, sequoia, peony, pepper tree, elm, for coniferous trees usually less frequently e.g. 1-2 times for larches as well as 1 time for girl pine, juniper, stone yew) otherwise the quality of a bonsai can deteriorate quickly.
If the bonsai is pruned regularly, the new shoots will increase the fine branching. The branching tiers become denser, the leaf cushions finer. More and more our bonsai approaches the ideal we strive for, the quality improves.
Although most bonsai trees can be pruned all year round, maintenance pruning is mainly done in the growing season from April-May to mid-August. The injuries are relatively small and can thus be "repaired" quickly by the bonsai. Wound healing is much better in the growing season and can still be promoted by wound closure agents.
Unfortunately, many tree species branch only sparsely and unwillingly. This is a problem for bonsai design. Of course, we don't want a tall, slender bonsai that shoots up into the air. Our ideal is usually a compact form with many branches and small leaves.
By leaf pruning, we can "coax" such a tree species to quickly branch finer and grow smaller leaves.
Full or partial leaf pruning involves removing all or a large portion of the leaves, as well as all buds at the end of each shoot. After a few days (e.g., Chinese elm bonsai) or weeks (e.g., horse chestnut), the bonsai will completely resprout. In the process, many "dormant buds" are activated and branching increases significantly. Usually the new leaves are also much smaller