Japanese Gray-Bark Elm Bonsai – Zelkova serrata

Zelkova is often listed as a replacement for American Elm since it has roughly the same vase shape and grows 90 to 100 feet tall with a 60 to 80 foot spread. Zelkova is massive, with the trunk capable of growing to four feet or more in diameter. It has a moderate growth rate and likes a sunny exposure. Branches are more numerous and smaller in diameter than American Elm. Leaves are 1.5 to 4 inches long, turning a brilliant yellow, orange, or burnt umber in the fall.
This elm is a native of Japan and China and is related to the Ulmus genus, which is the genus of the European and American elms. It is deciduous with small ovate, serrated, pointed leaves and smooth gray bark. It is a vigorous grower and is most often used for broom and group plantings. Root-over-rock plantings are also common. The gray-bark elm is considered by some to be the classic broom style tree.
Lighting: Full sun to part shade. During summer in southern part of USA, do not expose the tree to direct sun during the heat of the day.
Temperature: Zones 5 through 8. Make sure the tree has good winter protection.
Watering: Allow the soil to dry slightly between waterings. Spray the foliage with water daily during the summer.
Feeding: Feed every 20-30 days with a slow-acting fertilizer during spring and again from late summer through mid-autumn.
If you prefer to use chemical fertilizers, feed every other week using a half-strength solution of a balanced fertilizer such as Peter’s 20-20-20. If the fertilizer you use does not contain trace elements (minors) then you may need to treat with chelated iron a couple times a year.
Pruning and wiring: The gray-bark elm is usually shaped exclusively by pinching and pruning, but wire can be used. Wiring may be done any time from late spring (after the leaves are set) through mid-autumn. Structural pruning is done in winter so that the tree will lose less sap and so that the branch structure may be more easily seen. The foliage is developed by pinching back the new growth during the growing season. Wait until new shoots have at least 4 sets of leaves, then pinch back to 2 sets of leaves. (アコーホテルズ)
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