According to Washington State University, there are more than 200 varieties of Japanese maple. This tree, which is native to Asia, is a popular landscaping tree because of its genetic diversity. Japanese maple can grow into a 20-foot-tall vase shape with red leaves that resemble a western maple, or it may take on a low-growing, dense, shrub shape with lacy leaves. Because of the unusual shape of some Japanese maples, dwarf varieties are a popular choice for Bonsai culture.
Place a Japanese maple bonsai in a sheltered location protected from wind that can dry out the soil or push the tree over. The tree should be placed in semi-shade in the summer, but may remain in full sun from fall until spring.
Prune the tree in spring when new growth occurs by pinching back unwanted shoots, using pruning shears. Pinch large leaves off at the base. Smaller leaves will regrow on the leaf stems. Prune shoots once they reach four to five nodes long. A node is a point where a leaf emerges. Prune all shoots to ½ inch longer than you desire them to be to account for dieback.
Re-pot your tree in the winter when it is dormant so that it will not be shocked by the root-pruning process. Winter is also a good time for pruning large branches.
Water your tree with just enough water to keep it consistently as damp as a wrung-out sponge. Use a large water dropper to control the amount of water placed on your plant. Check your tree twice daily to ensure that it does not dry out.
Remove all the foliage from healthy, strong Japanese maple bonsai trees every two years to produce new buds and more branches, using pruning shears. Skip defoliating any year that you transplant or otherwise root-prune your tree.