Serissa Bonsai Tree Care Guide
Serissa foetida is a small subtropical evergreen native to wet woodlands and meadows in regions of India, China, and Japan. Also known as Tree of a Thousand Stars due to its abundance of small, star-shaped flowers, this shrub grows to a maximum height of four feet in its natural environment. The plant takes its species name from the unfortunate tendency of the bark to give off an unpleasant odor, but don't let that deter you as the scent is not usually noticeable except to a mild extent during trimming. This plant is the only species in its genus and is also sometimes referred to by its old name Serissa japonica.
The tiny leaves on this plant make it very desirable as a bonsai, even though the care can be a little fussy. The ovate, opposite leaves are only ¼ to ½ inch in length, dark green and glossy on some varieties, variegated with lighter green edges on others. The bark is flaky and gnarly, giving even young trees an old look. It is known to flower all year round in the right conditions, although heaviest blooming is typically from spring to fall.
Serissa can be grown indoors but it does better if kept outdoors in the warmer months. It should be brought in once nighttime temperatures dip below 50°. This plant also does well if wintered in a cool greenhouse. It should not be moved suddenly from one temperature extreme to another as this species does not like abrupt change.
Serissa likes a lot of sunlight but heat stress can yellow the leaves, so it's a good idea to offer afternoon shade. If grown indoors they should be placed in a south or east window and ideally given some artificial light. Insufficient light causes leggy, undesirable growth.
Pay close attention to watering with this species as it is averse to wet feet. The soil must be well-draining and you must avoid over-watering. Allow the bonsai to become somewhat dry between watering's. Unlike many plants, this species can be a vigorous grower during winter so it will need to be watered accordingly. Misting is beneficial, just be sure not to spray the plant while flowers are in bloom as it will ruin them. A humidity tray will also help keep the moisture level high enough.
Serissa should be fertilized bi-weekly between early spring and early fall, and once a month in the winter. We recommend a low-nitrogen, slow-release formula applied in pellet form. Do not feed when the soil is dry.
Serissa is suited to most bonsai styles besides formal upright. It is particularly suitable for root-over-rock, forest plantings, and shohin. Aerial roots sometimes form.
Prune growth in early autumn. Pruning back to the second pair of leaves is best in order to avoid leggy growth of the limbs. This plant responds well to ramification and directional pruning. Clip and grow is an effective way of shaping this bonsai. Be sure to remove spent blooms as they occur as this will stimulate further flowering.
Wiring works well due to the daintiness of the branches. Just be careful of the delicate foliage while wiring and watch for cutting in since these are vigorous growing plants.
This may be carried out most easily by cuttings. Softwood lengths may be taken in spring or early summer, and semi-hard cuttings in late summer. Rooting of these cuttings is helped along by bottom heat.
This needs to be carried out during the growing season rather than in winter. S. Foetida does not tolerate being root-bound so you should repot young plants every year and older ones every two or three years. Fast-draining soil is highly recommended; if you live in an arid climate it's a good idea to add some organic material in order to retain some moisture so that watering doesn't have to be done constantly. Root pruning will stimulate the growth of root suckers. These can be trimmed unless you want them to create a forest.
Insects/Pests & Diseases
Serissa bonsai can be vulnerable to scale, mealy bugs, and aphids (which prefer new growth). Scale can typically be seen as brown bumps on the tree. These must be removed by hand as this hard shell is impervious to insecticide. Afterward, the areas where they resided must be wiped down with insecticidal soap or treated with neem oil, as the eggs are harbored underneath the brown protective coating.
Mealy bugs can be difficult to eradicate, however there are products designed specifically for these pests. Treatment will have to be repeated after about a week and a half.
The most important thing to remember is that pests tend to attack when a tree is weakened or sick. Watering properly and giving your bonsai plenty of bright light will help keep it healthy and pest-free.