Wiring is mostly applied in the initial stages of structuring a bonsai, but it will continue to a lesser degree throughout the life of the tree. So mastering the technique of wiring really is a necessary evil.
The sole purpose of wiring a bonsai is to change the direction and shape of the branches and trunks to make them conform to your concept of the perceived design. Therefore you should have in mind what you want the tree to look like before you start.
Before you wire a tree it will be helpful if you stop all watering for a day or two beforehand. This will stop the turgidity (swelling with moisture) in the tree causing the branches to become slightly limp and therefore less likely to snap when bent. However, do not be too enthusiastic in this practice or the tree is likely to be droughted and will die.
The way wiring works is that in bending the wood you stress and sometimes damage the cells. The tree, while repairing the damage, grows into the shape you choose.
Bonsai wire is available in sizes from 1.0mm to 6.0mm. The wire you use should be about one third of the diameter of the branch to be wired. Some drastic bends may require multiple wires placed tightly together.
A way to determine the proper size wire which I use, is to hold a wire which you believe to be the proper size, about one inch from the end of the wire and push on the branch you are going to bend with the end of the wire. If the wire bends you will need to go to the next larger size. If the branch bends, then you should have the proper size. With practice you will learn which wire to use by looking and by knowing the species.
When wiring consider the tree's individual characteristics. Some trees are easier to wire at certain times of the year. Different parts of a tree will vary in the length of time necessary for the branch to set. Some varieties will tolerate drastic wiring and others will not. You will learn all this by reading and experimenting.
Older, stiffer branches will take longer, and you may have to bend them little by little every few weeks. Younger branches will bend easier but the wire will have to be removed sooner. Every plant is individual and it is only with experience that you will learn just how far you can go without snapping a branch, so take it easy at first.
If your branch does break, leave it as it is and apply sealing paste. Do not move the branch for the rest of the season and it will likely heal. Quite often, if you are making a drastic bend, you will hear the wood cracking. If you do, stop and examine the limb for any breaks in the cambium, if there is a break leave the branch alone. If not, 'carefully' continue the bend and listen carefully. If you hear any additional cracking stop and wait for next year.
The best wiring is evenly spaced, has no crossing wires, is unobtrusive and has the end of each wire before or at the end of each branch. The most important thing to remember is that the starting wire should be secure to either the trunk or to a branch by at least two turns. Wiring should be slightly tight but not so tight as to inhibit growth. If it is too loose there will be no strength and the branch will not hold in place. The ideal angle is 45 degrees when viewed from all sides.
In order to make wiring easier there is a general order for wiring trees. Start at the bottom of the trunk and gradually move upwards. After wiring the trunk, wire the first branch from the base to the tip. Proceed to the second twig on the same branch and so on. When you have wired all the twigs on the first branch, repeat the process with the second, third and fourth branch. Finally, start wiring the top, beginning at the base and proceeding to the tip.
There are basically three different modes of branch growth: forked, alternate and opposite. You can find diagrams in many bonsai books that show you how to wire different branches. Cut a couple of branches from your yard to practice on.
Forked- By wiring two branches of the fork with one wire, each branch holds the other. The important thing here is that wiring at the crotch of the fork should be secure and firm. The procedure is to begin at the fork, holding the wire at the back of the fork with one hand and then bringing the wires around and through the fork from the front, to form an upside down "V". Wire a couple turns on one branch and then, after wiring the other completely, return to complete the first one. If you are going to wire only one of the branches, wrap a couple of turns on the one that is not to be wired which should be enough to hold the other.
Alternate- This is the most common wiring that you will do. When you are wiring, you should try to wire two branches at a time since this acts to secure the beginning of the wiring on each branch. Start by treating the lower branch and the main trunk as a fork. After doing a couple of turns up the main trunk, wire the lower branch. This is the same procedure that you would use if you want to wire only one branch, or an opposite branch. After wiring the bottom branch, continue up the trunk to the higher branch.
Before bending a branch make sure your tree and pot are secure. Carefully and slowly with both hands bend the wire, NOT the branch, where you want the branch to be. Avoid twisting the branch or trunk. Think about the bend you want to accomplish and bend it once.
When bending a branch downward, the first half turn of wire should come over, then under the branch. When bending a branch upward the wire approaches from below.
The amount of time to leave the wire on is dependant on several variables. One is the size and age of the branch or trunk being wired. Conifers, especially junipers, may take several years to set, during which time the wire may need to be removed and reapplied several times to avoid damaging the bark. Some deciduous species and tropicals may set in a matter of a few weeks. It is better to leave the wire on longer than you think is necessary, as long as it is not cutting into the tree. Sometimes the tree will revert back to its original form over a period of a few weeks, so it is better to wait as long as possible.
You will find that if wire is left on a trunk or branch for too long it is likely to bite into the bark causing unsightly scarring. This is not to bad on coniferous species which will usually heal over in time. On deciduous species the scarring is likely to be permanet. Always keep a watchful eye out for this problem and remove the wire immediately if you see this happening. If the branch moves back replace the wire in a slightly different position until the branch has set
Wire can be expensive so it is tempting to unwind it once it has served its purpose in order to use it another time. However this is risky business since it is much easier to damage the bark or snap the branch when working in reverse. The branch will have grown, so the wire will be tighter than when you first applied it, and will be full of kinks making it difficult to manipulate. It is much safer to snip the wire away using wire cutters which cut right up to the tip of the jaws. If you are concerned about the expense of ' wasting' wire in this way, ask yourself this question, which is more valuable to you, a few inches of wire or a developing bonsai which you have laboured for hours and nurtured for years.