TRIMMING

Trimming is the removal of small branches or foliage. We trim bonsai for several reasons:

1. To keep the tree small and in the proper shape;
2. To remove parts of the foliage that are unattractive or in the wrong place (grooming);
3. To allow sunlight and air to reach other foliage;
4. To selectively retard the growth of the trimmed branch; and
5. To encourage sprouting of new buds in other places on the tree.

Trimming is one of the most important activities for shaping the tree and may be done throughout the spring and summer. To keep the shape you want, simply remove the new growth which develops outside the desired outline. Branchlets that grow straight up or down or cross other branches should be removed. If you want a branch to thicken, do not trim it; let the foliage grow wild on that branch all season and then prune it back the next year. To keep a branch thin, trim it repeatedly and thin out the foliage. In this way, you can balance the appearance of the different branches. Usually the top of the tree needs to be thinned more because it grows faster; and you want to keep the top branches thinner than the lower ones.

Trim the end of a branch just past a bud. Buds are usually at the base of each leaf. Whichever bud you leave on the end of the branch will sprout, and then the branch will grow in that direction. Thus, if you want the branch to grow to the right, leave the end bud pointing to the right. Do not leave the end bud on top because the new branch will grow straight up. Trim at an angle close to the bud, being careful not to damage it. Except for some conifers, most trees will bud back when trimmed. This means they will sprout branches from older wood. These dormant buds are suppressed, however, by hormones called auxins produced in the growing tip of the branch. When you cut off the end of a branch, you remove these hormones; and the buds on the rest of the branch will sprout. For best results, let the tip grow out for five or more leaves and then cut it off. This way you will remove more suppressing hormone. If you already have enough branches and just want to keep the shape you have, simply pinch off the tips of the branches or the unwanted buds whenever they arise. However, do not remove all the new growth.