Scientific/Botanical Name

Zelkova serrata

Description

This is a deciduous tree with a distinctly upright habit. The branches create a wide and beautifully-shaped arc. This tree is heavily favoured for use in the art of bonsai, and it is particularly suited to the broom style.

Position

This tree is grown outdoors in a sunny aspect: A situation that receives full morning sun and filtered afternoon sunlight is optimal. If exposed to hot afternoon sun, leaf-burn will occur. If intense sun cannot be avoided, the use of some form of screening device is advisable. This tree must be given protection in areas where frost poses a threat.

Watering

The depth of the container and the climate will determine the watering schedule. To keep the soil moist, twice-daily watering may be required for shallower pots in hot, sunny locations. Less water is required in colder months, but soil should not be allowed to dry out.

Feeding

Regular feeding with an organic fertilizer is beneficial to the tree – and this should be carried out from spring to fall. A feeding schedule can either entail the application of half-strength fertilizer on a weekly basis, or the application of full-strength fertilizer every two weeks.

Leaf and Branch Pruning

Branches and twigs that spoil the look and symmetrical shape of the tree should be eliminated. Care should be taken during the removal of the sprouts that form on the branches and the trunk of the tree.

Re-potting & Growing Medium

Young trees should be re-potted every spring for greatest success. More mature trees need to be re-potted every second or third year, usually when the roots become pot-bound. A rich but easily-drained soil is best, and the addition of Fuji grit is an excellent amendment that aids drainage. When planting or re-potting, it is imperative that dry soil is used, and pressure should not be applied to the soil. Instead, the soil should be settled by a gentle back and forth shaking of the container. Once the tree is planted or re-potted, it should be watered immediately.

Wiring

Wiring is best carried out during the summer months. Great care should be exercised to prevent damage to the thin branches that can be easily broken.

Zelkova bonsai is highly resistant to diseases. Roots of immature plants are apt to appear above soil level. These need to be covered with a thin layer of soil to ensure thicker roots. More mature roots may be left above the soil for an appealing and visual impact. The green leaves of the tree impart a sweet-smelling fragrance during cold weather, but the fragrance is no longer discernible once the leaves have changed colour.