The word bonsai literally means tree in a tray. Bonsai is a combination of art and horticulture in which a tree is miniaturized by carefully limiting the roots and growing the tree in a shallow tray. Bonsai is a name for both the tree being grown, and the practice of growing the tree. Although many herbaceous plants may be grown as bonsai, the practice of growing hardwood trees such as juniper hearkens back to the roots of the art. Juniper varieties such as the dwarf juniper shrub are hardy throughout much of the United States and have smaller needles that will give the illusion of a larger tree. This makes juniper a perfect plant for bonsai culture.
Position a juniper bonsai tree tray in a location where it is protected from the wind. Wind will dry out a bonsai's container soil, and can push over a tree or twist and break the limbs.
Protect the tree from the sun during the summer, moving it to a location with shade. A bonsai juniper can withstand full sun from fall through spring, but the intense summer sun can scorch, scald or dry a bonsai tree.
Water the juniper bonsai as needed with a large dropper or a kitchen baster.
Re-pot your juniper every three to five years. Re-pot in fall when the tree goes dormant to eliminate the shock of transplant. Remove 1/3 of the root length and the tiny feeder roots from the tree. Select bonsai soil that is 1/3 clay, 1/3 sand and 1/3 humus. Screen out dust-sized particles with a sieve to avoid compacting the soil around the roots of your tree. Work the soil around the roots with a chopstick to remove air particles. Cover the soil with moss to help hold in moisture.
Fertilize your tree every two weeks with a water-soluble (20-20-20) fertilizer from late spring to early summer and from mid-September to mid-November only. Fertilizing year-round will produce excessive growth.
Prune your juniper bonsai. pinching back the branches to the desired shape. Pinch the branch ½ inch longer than you want it to be. The ½ inch at the end of the tree will die back, leaving the bonsai exactly the length you desire.