The Japanese elm is a deciduous tree which is native to Japan, Korea and Taiwan. It can reach a height of 30 meters (100ft) and develops the characteristic broomstyle shape with a straight trunk fanning out into many branches and twigs.

The bark is grey and smooth and the young shoots are reddish at first. The leaves are simple and ovate to oblong-ovate with serrated margins, rough on top and glabrous on the underside. They are dark green throughout the summer, changing to yellow, orange, red and purple in autumn. The leafsize decreases quickly when the zelkova grows in a pot. The Japanese greybark elm is a classic Japanese bonsai and the prototype of the broomstyle, but it can also be styled in other upright shapes. The species can tolerate a slight frost and is easy to care for.

If you need help identifying your tree, try our Bonsai tree identification guide.

 

Specific Bonsai care guidelines for the Zelkova Bonsai Tree

Position: The Japanese greybark elm likes a place in full sun during the growing season or, if the sunlight is very intense in your country, semi-shade during the hottest weeks. In winter the greybark elm should be protected from frost, especially when it is planted in a shallow bonsai container. A cold but frost-free greenhouse, garage or shed is a good winter place for the zelkova.

Watering: Water the zelkova regularly and don't let the rootball dry out, but take care not to overwater the tree. Overwatering can cause root rot. In winter keep the rootball slightly moist. Avoid using very calcareous water.

Feeding: Apply solid organic fertilizer every four weeks or use a liquid fertilizer every week during the growing season. Use a fertilizer with a balanced N-P-K ratio.

Pruning and wiring: Let the new shoots grow until they have produced 4 to 6 leaves and then cut them back to 2 leaves. After the leaves have fallen, carefully prune thick twigs and overly long shoots. The winter silhouette and fine ramification of the Japanese greybark elm are extremely important and its nicest feature. It is also important to have a scarless trunk and a perfect nebari. Young zelkovas can be defoliated in June in order to promote the ramification. Older trees can be partially defoliated by removing the larger leaves in order to let more light reach the smaller leaves inside the crown. But keep in mind that the precondition for defoliation is always a strong and healthy tree. 

Wiring is best done in autumn, winter or in spring before the buds open, in any case when no leaves conceal the ramification. Young twigs often grow crooked and messy and must be corrected for a perfect broomstyle winter silhouette. Traditionally in autumn the branches and twigs of younger specimens are tied together in bundles and the bundles again are tied together, in order to promote the broom shape. In spring, before the buds open, the wire or string is removed.

Repotting: Repot the zelkova every two or three years, old big trees less often, and prune the roots carefully. The development of a perfect radial nebari is an important goal. Zelkovas are usually planted in shallow oval or rectangular pots. Use a standard soil mix. The ideal pH value is 5.5 to 6.5.

Propagation: The zelkova can be propagated from seed and cuttings. Greenwood cuttings can be taken in summer, hardwood cuttings in winter. Airlayering is also possible.

Pests and diseases: The zelkova is hardly bothered by pests and diseases. Aphids, leafhoppers, gall mites, spider mites or leaf spots can occur in rare cases. Use a specific pesticide and check the growing conditions if the tree is attacked by one of these pests.

For more detailed information on these techniques, try our Bonsai tree care section.

 

 

Example of a Zelkova (Japanese elm) Bonsai tree

Zelkova, Japanese elm Bonsai