Chinese elm is native in China, Korea, Taiwan, and Japan. This is the most popular species of elm for bonsai, because of the small leaves and fine twigs.
This bonsai can usually tolerate some frost but it depends on the region it was imported from. Trees from the northern part of China seem to be more frost-hardy than those from the southern part. Depending on the temperatures of their winter period Chinese Elms can be either deciduous or evergreen.
It is a very forgiving tree and this makes it very popular among beginner bonsai enthusiasts.
Chinese elm grows well in full sun and also in the partial shade. In mild climates, it can stay outside during the winter. If bought as an indoor Bonsai, it can be placed outside during the summer and in winter it is best to take it into a cold frost-free room.
It must be watered generously as soon as the soil gets dry. Completely dry soil should be avoided as well as permanent wetness.
During the growing season the tree should be fed well. It doesn’t require a very special fertilizer. If it is kept in a cold place during winter it shouldn’t be fed during dormancy.
It responds very well to frequent trimming which produces a dense ramification and it also buds well from old wood after strong pruning. Allow shoots to extend to 3 or 4 nodes before pruning it back to 1 or 2 leaves. The elm can be shaped very well with wiring.
Younger Chinese Elms should be repotted every one – two years, older and large specimens can be repotted in longer intervals. Spring is the best time for repotting. This tree has no special soil requirements, but it should be well-drained. A standard soil mixture can be used as well.
Pests and diseases
Chinese Elm is often infested by spider mites or scale when the humidity is low. Appropriate pesticides should be used and frequent spraying with water might help additionally. Spraying this tree with thinned lime-sulfur or systemic pesticides can make it drop all its leaves, so avoid using these products.