Traditionally the trunks and branches of bonsai were shaped by using long-term pruning and hemp rope for binding. Wire is the modern tool we use to accomplish the same result with much less time and work. There is a lot of misinformation about wiring out there and if you read long enough on the internet you will become convince that any wiring choice you make is either the only way to do it correctly or the absolute worst possible choice. Take heart, wiring your bonsai tree is not complicated and you can successfully wire your bonsai if you follow a few simple rules.
What kind of wire should I use?
Whatever you have on hand or can get cheaply. I have found no meaningful difference in the different types of wire. So use copper, aluminum or anything else that allows you to wrap the branch and it holds the shape.
What width wire should I use?
You want to use a wire that is about a third the width of the branch you want to shape. If the wire is too thin then the branch will not hold the new shape and if the wire is too thick you end up wrapping the branch around the wire instead of the wire around the branch. If you are not sure what width to use give it a test run, just be sure to only bend the branch slightly while testing. If you can move the branch and it holds the new position then that width of wire works.
How do I wrap the branch?
The basic rules is that one wire does two branches. You cut a piece of wire about three times the length of the branch you want to shape. You take the center point of the wire and start wrapping the branch you want to shape and a second nearby branch. The second branch can also be shaped or will service as an anchor for the wire on the branch you are shaping. Moving away from the trunk, wrap the branch with the wire maintaining near a 45 degree angle. Adjust the angle to avoid any foliage or smaller branches coming off the target branch. When you reach the end chip off the excess wire. Repeat the process for the second branch.
That is the standard method and it works well. But as long as you get wire on your tree and it holds the branch in the new position without doing damage you are getting the job done. Focus on the result, not the technique.
Okay, I got it wrapped, now what?
You want to move the branch into the desired position. The goal is to move the branch only one time, since each time you adjust the branch you could be doing damage. Get the branch how you want it, but with as few adjustments as possible.
What if my wiring is not neat?
If the wire holds the branch in the desired position it is doing its job. Neatness only matters if it bothers you. There is no practical benefit to the wiring looking good.
What time of year should I wire?
You do not want to wire an outdoor bonsai when it is frozen, but other than that wire whenever you have time. The season does not matter.
How often should I wire my tree?
The more you wire the better the bonsai. Just be careful to give the branch time to recover if you have previously wired it. You should allow several months for recovery.
Can I cross wires?
You absolutely can, but it is not ideal. If you decide to cross wires keep in mind that crossed wire will cut into the bonsai quicker than individual wires so whenever you cross wires give that area extra attention to make sure the wires are not damaging the tree. The same can be said when you are using thin wiring.
How long should the wire stay on?
As long as possible. You do not want the wire to break the bark. If the wire is on too long you will start to see the bark swell around the wire. At this point the wire in the area that is swelling needs to be removed immediately.
How do I remove the wire?
When it is time to take the wire off use wire cutters. Cut the wire(not the tree) in small sections that either fall off on their own or are easily removed. Do not unwrap the wire. The wire has moved the branch into a new shape and any twisting or pulling could damage the newly formed wood. You do not want any of the falling wire scraps to stay in your soil, so before cutting it is a good idea to cover the base of your bonsai tree.