I've never kept Serissa in my personal greenhouse, but I've grown very fond of them and this year, if I feel confident that I can keep it at 50F or higher over the winter, I'm going to add one a Serissa to my personal collection.
What makes them such an appealing bonsai? Some people will say the flowers, which arrive - usually quite abundantly about 2-3 times a year. The leaves are well suited to bonsai as well. Solid green or variegated they're small, oval and shiny- and usually evergreen. But what I really love about Serissa is the trunk and the bark once the tree has (at least started to mature) Gooved and twisty they have a ton of character. Adding to Serissa's general popularity is the fact that it grows quickly and ramifies very well. (Ramification is the growth habit that results in many fine branches.
Serissa is naturally an evergreen or semi-evergreen shrub found in open sub-tropical woodlands and wet meadows in southeast Asia, from India, and China to Japan.
The thing that I find funny about Serissa is that some people think its a piece of cake to grow and for others "it's impossible". I think there are a few factors contributing to that rather wide range of opinion.
Serissa does not like change and to prove it to you, it will drop leaves quite freely whenever it's unhappy. And what makes serissa unhappy? Under-+watering, over-watering, air too dry, too hot, too cold or because you moved it (haha reminds me of a ficus). But once you recognize that, you're half way to growing it successfully (kinda). I realize it sounds rather perverse, but I like it when trees let me know they are not happy. It means I can find out I'm doing something wrong, before its too late.
They love sun and they love water (naturally found in wet meadows is a strong clue). You don't want to keep it wet all the time, but never let the root ball dry out completely.
Indoors, give it good light- 6-8 hours of direct light is good, but not on a windowsill as the temperature varies too much to make Serissa happy. If possible grow it outside during the summer. Bright morning sun - late afternoon shade.
Feed your Serissa sparingly with a balanced fertilizer once a week during the growing season.In the winter if your tree stops growing, don't fertilize also if the tree is not healthy - no fertilizer. When you do fertilize- water it first so you don't burn the roots.
The Serissa tolerates an annual hard pruning in the spring, if necessary. Young trees are trimmed back to 2 leaves when the shoots have produced 4 – 5 leaves. Older trees are pruned thoroughly after flowering. About every three years you'll need to cut the branches back to old wood to maintain control of the shape. Wire any time but do it carefully as the branches and shoots of serissa are quite delicate. Remove the wire after about 6 months or when you can see that it is too tight on the branch and starting to cut into the bark.