Tips & Care: Pinching and Leaf Trimming (Defoliating) your Bonsai

What is the idea of trimming your bonsai?
Remember that during late spring and throughout the summer bonsai can quickly become overgrown, losing their shape and overall structure. The speed at which they grow depends on many factors, such as age, species and also the watering and feeding regime.To keep the growth balanced and in shape, trimming is necessary and essential for the development and maintenance of your tree, helping to create miniature trees, rather than overgrown bushes.

Trees should be allowed to have periods of free growth to keep them healthy. There is a close relationship between new shoots and new roots, so you can be sure that when a tree's shoots are extending, so are the roots. The extent of growth allowed will depend upon the stage of training. 

A tree in the development stage will benefit greatly from a period of free growth, which will help to thicken up the branches and trunk. For mature bonsai, growth should be kept more balanced and so shoots are scissor trimmed, pruning particularly vigorous shoots harder, before they begin to sap strength from other areas. The result will be shorter internodal lengths and more compact growth. However, if a branch is weak, allow it to grow to extend to provide it with extra strength the top of the tree (which is the most vigorous area in most species), with the lowest branches being weaker, (azaleas and kiyohime maples are notable exceptions to this growth pattern). 

This should always be taken into account when pruning or trimming trees, therefore it is usually necessary to prune harder higher up on the tree. If a bonsai is left to grow unchecked, the top will quickly become dominant, with the fine shoots near the apex becoming thick, ugly and out of scale.

Pinching the candles on pine trees once they are fully extended will result in back budding and compact growth. It is worth taking out the dominant central shoot, to allow more strength to be channeled into the weaker side shoots. If the candles are allowed to develop into shoots, the size and strength of the tree will be increased. These shoots should then be cut to the required length in midsummer, or have the end buds removed to encourage denser growth the following year. 

Removing all the candles in spring as they start to extend will produce new buds both at the tip and further back. Some of these buds will open in the same year, producing compact growth with smaller needles. By using these techniques and also by controlling the watering and feeding while the needles are opening, their length can be considerably reduced. Do not, however, try for tiny spruce-like needles as these look unnatural and can make the tree weak once a twiggy structure has become established, summer pinching is a useful technique to maintain the tree's shape and to develop greater ramification. For juniper, cypress and other similar conifers, hold the foliage in one hand and 'pluck' the new growth. The shoots will be removed cleanly, whereas using scissors would cause more browning at the ends, especially in dry and sunny weather. 

With deciduous trees, such as maples, zelkovas, elms, beech and similar species, pinch out the growing tip once new shoots begin to unfurl and extend past the first set of leaves deciduous trees usually grow far more rapidly than conifers, with new shoots extending quickly do not prune just to maintain a silhouette. The interior of the tree will quickly begin to die if it does not receive adequate light and ventilation, so this should be considered. Lack of light and air flow can also encourage pests and diseases. Thin out dense areas of foliage to ensure that whole branches remain healthy. Leaf pruning deciduous trees can help considerably, preventing die-back when pruning, if possible, leave the bud at the end of the shoot pointing in the direction in which you require the growth to extend. This practice is known as 'directional pruning' and is a useful technique which reduces the need for wiring if removing large branches, always ensure that the remaining wound is concave, so that it will heal neatly and quickly. 

Seal with cut paste or similar (remember you can even use school glue). An ideal time to remove large branches is during midsummer, after the initial burst of spring energy has subsided. This ensures a smaller callous and less bleeding, although branches can usually be safely removed at most times of the year. For conifers, consider the option of creating a jin pruning deciduous trees in late winter or early spring enables their form to be seen clearly. However, make sure that you are aware of any branches that have died, so that you do not remove a live branch and find that you have unwittingly left a dead one! Trees that have been winter pruned will benefit by being given protection from the elementswhen removing branches, if unsure whether the branch should be removed completely, prune back hard first. Leave some buds that could grow back if desired, so that your options are left open'Finger pruning' is at the top of the list of skills needed.For Junipers and Cedars and other conifers, this involves pinching new growth off wherever shaping and eliminating is carried out.Simple in theory, just support the tree or branch with one hand and take the new growth between your thumb and forefinger in the other. Remove with a sharp twist, but avoid pulling on the branch or tree.It will take some practice to be comfortable with the technique. 

Rather than damage a valued bonsai, gain some familiarity first by performing it on a small bush.Once you can remove the growth cleanly without tugging on the plant, you're ready to use it on your bonsai. For deciduous trees, such as Maples,  Chinese Elm or others, scissor tip pruning is best. Trim the new shoots back to your imagined point based on the sketch.Leaf pruning or defoliation is also common for some deciduous trees and bushes, such as a ficus. 

Carried out in mid-summer, you simply remove half of the leaves with a pair of fine scissors. Leave the stems intact. For this, when you trim outward, you want to trim back the shoots but just after the next series of leaves. Finally, leaf pruning is used for both tropical and deciduous plants. This helps reduce the size of the leaves, get rid of unsightly leaves, and encourage growth by creating two growing seasons in one.