The gray-barked elm (Japanese zelkova) can be trained to form miniatures of the naturally grown forest trees, and will make beautiful bonsai. These bonsai elm are much sought after.
Unwanted sprouts. At budding time in the spring and after leaf thinning, sprouts appear at unexpected places on the trunk and branches, and these should be rubbed off or cut off. Aphids and other insects are exterminated in the usual ways.
Autumn. After the leaves have fallen, any disproportionate and undesirable twigs and shoots are removed, so as to enhance the symmetrical and delicate beauty of fine twigs and shoots which produce the atmosphere and image of a great tree throughout the winter.
Branches in a circle and a branch parallel to trunk should both be avoided. Branches alternating and spreading is the result to be desired In the spring, just before the buds burst, for the sake of possible improvement in the beautiful shape of the tree, twigs and shoots are cut back as short as possible. Then the renewing and rewarding beauty of the young leaves is awaited.
General Care For Bonsai Elm
Soil for growing bonsai should be selected to match the variety of plant. For potting soil for zelkova bonsai I use loamy soil from cultivated land or sandy loam from the mountains. The soil is sifted through a sieve, and used only after it has been well and thoroughly dried. The tree should be planted in the dry soil in the pan, and the pan shaken several times after planting. The surface of the soil is then leveled and immediately watered gently and thoroughly with a watering can. The soil should never be pressed.
Surface roots. When a zelkova bonsai becomes older, several roots become thick and appear at the surface of the soil. Such a “root-surfaced-on-the-soil” tree is much sought after and very ornamental. However, if the roots are surfaced when the tree is young, they never thicken; only roots in the soil will do so. After learning by bitter experience, I cover surfaced roots slightly with soil, and on this place moss.
As the roots develop, the moss becomes scanty and the roots gradually appear on the surface. Sometimes even when the tree is 14 to 15 years old the roots are not yet developed sufficiently to appear on the soil. I have several trees of the same age that do show surfaced roots. Bonsai merchants often show surface-root formations in young trees for commercial reasons, but this is not good for nice root formation on the soil later on.
Shading. In the hottest weather, July and August, the trees are shaded; I use marsh-reed screens.
Watering. Over watering is not good for the trees. However, as zelkova bonsai are grown in shallow pans, they dry out rapidly in the summer, and watering twice a day is necessary; but in other seasons once a day is enough. After the leaves fall in the winter, it is sufficient to give water once every other day.
The bonsai elm is a beautiful plant to learn how to grow bonsai, and it will give you joy for many years.