Zelkova, Japanese - - Zelkova serrata
Japanese Zelkova is a tough urban tree for residential shade and street plantings. It has a spreading, generally upright branching, vase-shaped habit. The crown is shorter and more rounded than the American elm. The bark is a smooth, reddish brown when young with prominent cherry-like lenticels. As the tree ages, the outer bark is gray-brown and often exfoliating exposing an orangish inner bark. Medium green leaves turn to shades of yellow, orange, brown, deep red to reddish-purple in fall. This tree will tolerate most soil types including those with a pH to about 7.5, but prefers deep, moist, well drained soils. It does well in full sun. Established trees are fairly drought and wind tolerant (if properly pruned). It is resistant to Dutch elm disease with good resistance to elm leaf beetle and Japanese beetle. Young trees are susceptible to frost so transplanting should be done in the spring. Pruning should be done in fall, and Japanese zelkova will require some pruning to develop a strong structure. The main branches should spaced along a single trunk, so they develop a secure hold on the trunk especially in urban areas. Branches should remain less than 1/2 the diameter of the trunk to maintain a strong form. Planting uses for zelkova include lawn, shade, and street tree, parking lot island, buffer strip, and bonsai.