Bonsai is an art form that involves the tray-planting of dwarf trees and the pruning or trimming of those trees to be aesthetically pleasing. They are used for ornamentation both indoors or outdoors. While the majority of trees that are used in bonsai can grow up to several feet in height, tray-planting keeps their size in check and pruning helps them maintain their design.
Remove branches that are dead or infested or have shown weak growth. These branches will be easy to spot, as they won't sustain foliage and will dry out.
Cut away branches that cross over each other or grow against the trunk of the tree. Branches that cross can rub against each other and destroy each other's bark, leaving wounds that make the plant more susceptible to disease and infection, as well as ruining the appearance of your bonsai tree.
Prune a bonsai tree to shape and direct the tree's growth. Heavier pruning will be required in the beginning of the tree's growth to form the general shape and growth pattern of the tree. Removing main branches that are growing near the base of the tree will help expose the one central branch of the tree.
Trim the roots to match up with trimming you have done above the tree. As you remove bonsai branches and leaves, the corresponding roots beneath the soil will still grow and the tree will grow more rapidly to make up for the discrepancy. There can be more roots than above-ground growth, but they should not exceed 30-percent more than the tree. Maintain the roots by always removing some of the soil and trimming away roughly the same number of roots as you do branches and foliage.
Use finger pruning with evergreen bonsai trees. Use your fingertips to pinch off any new branches or leaves that do not fit the design of your bonsai.
Cut deciduous bonsai, such as elm and maple, with bypass pruners. Branches and shoots can be trimmed back to any desired length.