Elm zelkova (Zelkova carpinifolia) and Japanese zelkova (Zelkova serrata) are two types of Japanese zelkova that are suitable for bonsai. Zelkova are actually related to elm trees but are not susceptible to the same diseases. The trees have small, green, fragrant leaves that turn bronze or golden yellow in the fall and a straight trunk that starts out green and turns to gray as it ages. Small, green flowers bloom in the winter.
Plant in a deep, fertile well-drained soil and give the plant full sun.
Grow the tree using any bonsai style. Broom style is the most recommended because of the way it develops a thick crown.
Repot young trees once a year and older trees--10 years or older--once every two to three years, depending on how jammed in the roots are. Always repot in the spring.
Wire the tree in the summer. Care needs to be taken because the branches are very thin and break easily.
Prune shoots back, leaving just one to two leaves.
Protect from frost if planted outdoors, or the tree will experience branch dieback and root damage. Moving it into a garage or shed for the winter will suffice. Indoors, keep the plant in a cool, sunny windowsill in the winter. The tree should go outdoors from May to autumn.
Water the tree heavily in the summer when the tree is growing and sparingly in the winter when it is dormant. Never let the soil go completely dry, but don’t let it get sopping wet either.