Training a bonsai tree is part of the art of creating a well balanced bonsai. The exact shape of the tree will depend on the style you are trying to create. Training young branches early is easier than trying to force an older, thicker branch into place. How quickly your bonsai will take its new shape will depend on what kind of tree you are training. Use thick wire that will not mar the trunk when you train your tree, and remember to move or remove the wire to prevent it from cutting the bark as the tree grows.
Prune and trim away any unwanted growth. How much you remove depends on the type of tree you have. Japanese pines need to be pruned over several seasons or you risk killing the tree. Many other trees, like Japanese dwarf junipers, are very resilient and will do well if you remove up to 70 percent of the initial foliage.
Wrap the branches to be trained with bonsai wire. Start at the base and wrap the wire at a 45-degree angle to the direction of branch growth. The more wraps on the branch, the more securely the wire will hold the branch in place. The first wire wrap on a branch bent downwards should be on top of the branch. Place wires on branches you wish to bend upwards on the bottom of the branch.
Be careful when bending the wired branches in the direction you want, especially when bending near the tree trunk. If you hear or feel the branch breaking, stop immediately and allow the branch to train at somewhat less of an angle. After a three or four weeks, try adjusting the branch again.
Leave the wire on the tree long enough for the new shape to transfer to the branch. The length of time the tree will need to be wired depends on the type of tree. Some trees, like junipers, take the shape fairly quickly and can have the wires removed after six or eight weeks. Other trees, like Japanese pines, may take six to 12 months to take the shape, depending on their age. In general, however, leave the wire on the tree for three or four months.
Remove the wire by cutting it off with bonsai tools. Don't try to unwrap the wire; you could easily damage the tree. Examine the new shape of the tree and re-wire any branches that aren't trained in the direction you want.
Throughout the wiring process, watch for buds and growth where you don't want them to be. If you see a bud forming on the trunk, simply rub it out. As you look at the tree, you may see small branches growing from the wired branches that aren't in balance. Either pinch these off or use bonsai pruners or fingernail clippers.