The Serissa is also called snow rose, tree of thousand stars or Japanese boxthorn. It is a subtropical small shrub with tiny white flowers that appear from spring through summer.

The Serissa is evergreen or semi-evergreen with fine oval, shiny green leaves and variegated coloured leaves. Flowers range from single white star shaped flowers, double whites and also pink.

Foliage and roots have an unpleasant smell if damaged. Except for its lovely flowers, the Serissa is valued for its fine ramification and rough grey bark. The Serissa is not easy to care for because the tree is very sensitive to changes in location and temperature. The correct name of this tree is "Serissa japonica" but most people still use the old name “Serissa foetida”.

Placement

The Serissa likes a sunny, wind-protected place outside during the growing season as long as the night temperatures stay above 50° F / 10° C. Drastic temperature drops are not tolerated. Avoid unnecessary changes of the tree's position. Serissa Bonsai do not tolerate frost. Place small plants in water trays to increase humidity in the summer.

Watering

Keep the root ball moist, but at the same time take good care not to overwater the Serissa Bonsai tree. It must never dry out completely. If the tree drops its leaves due to some changes in the growing conditions, continue but slightly decrease watering. The Serissa likes a neutral pH value (7).

Fertilizing

Apply a small amount of solid organic fertilizer every four weeks or use a liquid fertilizer in a low concentration every week during the growing season. Use a fertilizer with a balanced N-P-K ratio. In winter fertilize once a month with a low dose of liquid fertilizer if the tree is kept in a warm place. Do not fertilize unhealthy or not growing Serissa but you can use Seasol to help the plant recover. In autumn apply a fertilizer with added potash or increased potassium to develop flowers in spring.

Pruning and wiring

The Serissa tolerates hard pruning which should be executed in early spring, if necessary. Young trees are trimmed back to 2 leaves when the shoots have produced 4 – 5 leaves. Older trees are trimmed less as long they are flowering, but are pruned thoroughly after flowering.

Prune to shape as you will. Serissa bonsai trees respond really well to directional pruning and produce great ramification. But be aware that hard pruning will cause the Serissa bonsai to produce root suckers. The best time to prune Serissa bonsai trees is in early spring. Let the tree grow out in summer to help it handle heat stress then prune again in autumn if necessary.

Every two or three years the branches must be cut back to old wood in order to keep the tree shape compact. Branches and shoots can be wired at any time, but they are delicate and must be wired with great care. Remove the wire after approximately six months before it cuts into the bark.

Repotting

Repot the Serissa every two years and use a good quality open bonsai mix. Prune the roots only moderately. The roots smell unpleasant when they are cut.

Propagation

The Serissa can easily be propagated from semi-hardwood cuttings.

Pests and diseases

Aphids, root aphids or spider mites can attack the Serissa. Use a specific pesticide and try to increase humidity. Overwatering or bad soil can cause root rot. Then repot the tree, cut off damaged roots and plant it in fresh, well-draining soil. Try to improve the conditions for your tree.