Shaping Bonsai

The perfect bonsai should have an aged-looking trunk and a vigorous growth of branches and leaves. The proportions of the tree should be similar to those of natural growing trees in the country or in forests but in miniature. Perfect results can only be obtained by continuous intervention. This will involve frequent pruning of the branches, leaves and roots, along with wiring, which moulds the trunk and branches into various accepted styles of bonsai.

Pruning bonsai

Whatever the growing technique, the purpose of pruning is always to control the growth of the tree by managing the development of branches, leaves and later its fruits (by thinning out). This is why pruning is so important throughout the life of the bonsai. As with fruit trees, we must distinguish between pruning to form the shape of the tree and on the other hand for its care and maintenance. Both need special equipment for the delicate operations involved.

Pruning equipment

A set of good scissors or clippers, both efficient and well designed, is essential to produce trees which conform to the aesthetics of bonsai.
Branches should be cut with a pair of strong cutters and sometimes (older branches, for instance), a pruning saw.
There are two types of scissors, those with strong, thick blades and large, broad handles and those with short blades and long, straight handles. The former are for cutting leaves and the latter for nipping buds.

Pruning for shape

To a large extent, the quality of a bonsai depends upon this. Pruning should be carried out very early on trees grown from seed or propagated vegetatively (from cuttings, grafting or layering). However, it can be done much later on a tree collected from the wild.
As a basic rule, always cut back one of two opposite branches on the trunk. In this way, you will produce a tree with alternate branches in keeping with bonsai tradition. Beyond this simple fundamental rule, pruning for bonsai formation is intended to shape the tree to the form you want. Be discriminating when removing branches, since a branch cut from the trunk will not grow again and you may be left with an asymmetrical or badly-shaped tree. Any error in your judgment may be rectified by grafting on a replacement branch -but this is always a delicate operation and not guaranteed to succeed. Although there are certain rules (such as systematic pinching out of the tips to obtain a well  branched crown), this sort of pruning is generally a matter of common sense. It is obviously necessary to cut out suckers developing at the base of the trunk of a broom shaped tree, just as it is to cut back the leading shoot of a tree that you want to form a bushy shape, the skill being in selecting the right branch to take over as the new leader. Cuts should be clean, so the tree can heal quickly. This often means using a pair of cutters with slightly curved blades. For slightly thicker branches, the small hole left in the trunk should be filled with grafting mastic to accelerate healing and eliminate all traces of the scar where the bark has grown back. Where a pruning saw has been used, it is almost always necessary to trim the cut with a pair of cutters or the blade of a grafting knife.
Tools should always be sharp and clean. Sterilize the blade with a flame after each pruning, to reduce the risk of transmitting viral diseases.
At this point, it might be useful to stress the quality of the tools you use. Traditional Japanese bonsai tools are certainly not cheap, but they are perfectly adapted to the requirements of bonsai cultivation.

Maintenance Pruning

This is at least as important as formative pruning, since it also makes a day-to-day contribution to the effort of producing a bonsai of a particular style.
Maintenance pruning will vary, since any tree could be pruned several times during its growth. There are several different pruning methods that suit different species and cultivars of trees and you should follow the correct one.
In general terms, pruning for care and maintenance is intended to restrict the irregular growth resulting from the natural development of the tree. It is intended to promote harmony between the trunk and the branches and their foliage, which is essential to obtain a tree worthy of the name bonsai. Pruning for care and maintenance is repeated throughout the growing season to reduce the number of new branches by disbudding, to reduce the size of the leaves by trimming them and to shorten the shoots to inhibit their growth. This is an indication of the amount of care bonsai require for a large part of the year.

• DEBUDDING: This type of pruning is only for deciduous trees. Pinch the buds out with your fingernails when the first growth appears. This is normally done at the beginning of spring, although it may be done several times during the year on some trees (e.g. elm, maple, hornbeam). When carried out repeatedly it produces smaller leaves. The tree may be affected to some degree and so should be fed regularly with modest amounts of fertilizer.
• TRIMMING LEAVES: This mainly concerns trees with broad leaves, like chestnuts and oaks. Clip the leaves down by a half in late spring. Leaves clipped like this will drop off and be replaced with smaller leaves during the summer. Deciduous trees with small leaves can have their leaves completely removed (heavy pruning), the operation being repeated several times in the growing season. This is a radical practice which should only be carried out if the tree is quite healthy and vigorous.
• CUTTING OR PINCHING BACK SHOOTS: The most important maintenance operation on bonsai, since the quality of the tree's foliage largely depends on this. Pinching back helps preserve shape, by inhibiting the natural exuberance of the growth. The method may differ from one species or cultivar to another, depending on whether the tree is deciduous or a conifer.
• PINCHING BACK DECIDUOUS TREES: How often this is done depends on the growth rhythm of the tree. For a maple, it will be repeated several times in the season, whereas a hawthorn may require pinching back twice only, in early summer and early autumn.
  The technique is roughly similar for all species. It consists of nipping the shoots above a leaf joint, always leaving a pair of leaves on the branch. This operation will allow the branch to ramify and at the same time dwarf the new leaves. This method also encourages good sap circulation, called upon by the requirements of the branch. It goes without saying that flowering or fruiting trees should not be clipped until after flowering or fruiting has finished.
  Always collect the leaves you have cut. If you leave them lying around, your bonsai will look unkempt and the decomposing leaves will keep the soil damp and favor infection by fungal diseases.
• PINCHING BACK CONIFERS: While the reasons for doing this are the same as for deciduous trees, the technique is considerably different. First of all, it is carried out just once a year, generally in mid-spring, when the young shoots start to sprout. In most cases it is sufficient to remove one third of the shoot with the fingers. Do this by pulling lightly and the shoot should come away easily. Do not use scissors, for fear of cutting the ends of the remaining needles which could then turn yellow a few weeks later. Whereas a pine shoot should only be lightly pulled, it is necessary to twist shoots of a spruce as well. Unlike the other conifers, the juniper should be pinched right back throughout its growing season, which lasts from mid-spring until mid-autumn.

Binding and bending

As the art of bonsai developed over time, new methods of shaping and creating were added to the traditional techniques. Binding and bending are two such methods, and, when they are handled expertly, a gardener is able to achieve stunning results. The essential ingredients necessary for the job are patience, reflection, and knowing the load-bearing capacity of your small tree-in other words, true bonsai talent. The goal of bending and tying might be, for instance, to change the distance between branches.

Another way to influence the shape of a bonsai is to bend the branches and twigs downward, closer to the ground. The following examples may serve as a guide. When bending and tying, it is important to remember to cushion the places where the string or wire touches the branch. A piece of rubber or cloth will serve as a cushion.

Wiring and shaping

You can change the direction in which a branch, twig, or shoot wants to grow by wrapping it with wire and bending it into the direction of your choice. The wire should remain in place until the branch or shoot is growing in the direction that you have chosen- a process of cautious adjustment that is, however, only possible if a special technique is applied.

Experienced bonsai gardeners make use of this method when they want to bend a branch downward that is very straight and rigid, so that the tree will look older than it really is, or when they want to straighten out crooked branches or twigs. Gardeners will put up with the fact that their wired indoor bonsai will lose some of its beauty for anywhere from 1/2 to 1 1/2 years; that's how long wiring might take.

The effects of even minimal wiring and shaping are often much greater than an inexperienced bonsai gardener might expect. This is because, when only a few branches are wired, you allow more light to reach the inside of the tree, which in turn allows those branches and twigs within the grown to develop better, which changes the form of the tree.

Wiring, therefore, is not a technique that interferes with the development and growth of a tree. On the contrary. The only exception is when branches are bent down. This will slow down growth and development. Make sure, therefore, that the shoots at the end of a branch that is forced down are always pointing slightly upward. This is a sure sign that the branch is not drying out or dying off.

It's important that you use the proper wire of the proper thickness. The best wire is anodized aluminum wire. This wire is easy to bend and is not noticeable, because of its dark color.

The wire you use should be about one-third the thickness of the branch or twig that is to be wired. The wire should also be about one-third longer than the branch or twig. A small assortment of wires of varying gauges should be part of the tools and equipment of the bonsai gardener.

Small corrections using the wiring technique-a good way for a beginner to practice the method-can be done throughout the year. Shoots, however, should only be wired after they have ripened, meaning after they have begun to lignify. More extensive corrections should be done between fall and spring, or before the main growing phase. The wires should not be tied too tightly around the branch or twig, and bonsai gardeners recommend covering the wire with thin paper before wrapping in order to prevent damage to the tree. Observe the plant closely so that you will be able to react right away to small damages in the bark. Should you detect any damage, loosen the wire, even if the desired shape has not yet been achieved. Wiring two or three times in succession won't harm your indoor bonsai. You will harm your tree if you have to tear out a wire that has become embedded in the bark, however.

If, in spite of every precaution, a wire has become embedded after all, remove the portion that is not embedded with a wire cutter and leave the rest in the bark. There are many venerable, beautiful, old indoor bonsai that have been living well even with a piece of wire embedded in the bark.

It is also important to take a gentle approach when shaping a branch or twig wrapped in wire. It's helpful to test how far a branch or twig will bend "without pain" before wrapping the wire around it. Should the branch split anyhow, cover the injury immediately with tree wax, and, in the case of a larger injury, wrap it with raffia.

The following examples will show you the most important wiring and shaping techniques:

Wiring the trunk

The end of the wire is pushed at an angle into the soil at the back of the bonsai tree. Use a thick wire for wiring a trunk.

Wiring a branch

Even if you want to bend only one individual branch, the opposite branch must also be wired-it secures the wire. Start to wire in the middle of the branch whose direction you want to change. The angle of the wrapped wire should be 45°, and the distance between the turns should be even.

Wiring a twig

The thinner the twig, the closer you need to wrap it. Extremely thin twigs-those that are still green-should not be wrapped.
Make sure that you don't trap leaves under the wire.

The trunk, branches, and twigs are always wrapped in the direction of their growth: from below upwards. Don't leave the end of a wire loose; cut if off at the back of the branch or twig.

When bending a wired branch use the necessary force to accomplish the task, but be gentle. Use your thumb as a counter pressure to the force applied with your hand. This will prevent breaking or splitting.

Don't try to force a branch against a bend it has grown into naturally. Always keep the original direction of growth in mind when bending a branch. The first bend of a branch should be made close to the trunk, and the first bend of a twig close to where it grows out of a branch. Whenever a branch is bent downwards, it should, at the same time, be bent forward.