Chapter 130 Serissa japonica
130.1 Tree of a thousand stars, snow rose
A Serissa grove planting. This photo shows how these trees need to be pinched back constantly in the growing season to keep the foliage tidy. Link to original image.
130.2 Soil: Rich Mix
Ratio: 4 parts bark, 1 part coir, 1 part grit
Add-ins: dolomitic limestone (~5 lbs/yd), Tree-Tone (15 lbs/yd)
pH: ~6.5 (slightly below neutral)
Moisture: moisture retaining, free draining soil is essential. It must never dry out completely. Keep the rootball moist, but at the same time take good care not to overwater the serissa Bonsai tree. If the tree drops its leaves due to some changes in the growing conditions, continue but slightly decrease watering.
130.3 Light
Routine: Mostly sunny.
Summer: Mid-day shade.
130.4 Cultivation Notes
Personally I think Serissa is one the most challenging of species to use for bonsai, and definitely not for beginners. Healthy Serissa have tiny glossy leaves and produce numerous small white flowers throughout the growing season. Keeping them healthy is the challenge. They are extremely fussy about their growing conditions. They need fibrous soil that is continuously slightly moist (but not too wet), while also porous and free-draining. They also are sensitive to changes in light and do not tolerate drastic temperature drops.
Keep outside protected from wind during the growing season (i.e., when night temperatures stay above 50°F).
Even after accommodating their many requirements, my experience has been that Serissas are prone to dying back or dying completely without an obvious cause.
130.4.1 Potting & Root Pruning
Schedule: repot every two years. Prune the roots only moderately.
130.4.1.1 Top & Branch Management
Heavy pruning: Serissa tolerates hard pruning. Make cuts in early spring to build structure. Every two or three years the branches must be cut back to old wood in order to keep the tree shape compact.
Fine pruning: 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.
Wiring: 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.
Leaf pruning: Serissa will not tolerate leaf pruning.
Close-up of the surface roots, gnarled trunk and branches, tiny leaves, and flowers. Link to original image.
130.4.2 Feeding
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 trees that are unhealthy or not growing.
130.4.3 Pests & Problems
They can get aphids, mites, or scale, but I’ve not had much problem with pests
130.4.4 Winter Storage
From autumn to spring, keep in the house at temperatures between 50-68°F. The warmer the position the more light is needed. Try to provide high humidity, or mist regularly.
130.5 Propagation Notes
Serissas grow readily from cuttings dipped in rooting hormone and sunk in a 1:1 mix of peat and sand.