Water Jasmine is the common name for Wrightia religiosa, the variety used for bonsai. The name alone will tell you a lot about the plant. First of all, it likes plenty of water. Secondly, the flowers are as sweet smelling as jasmine. (Although it is not related.)
The plant is native in tropical Africa, Asia and Australia, where it is a fast growing, hedge plant. It is also a popular bonsai throughout the world. The trunk looks like a tree, usually has good nebari, it's easy to maintain and is fast growing. The beautiful flowers are one of the most popular reasons for growing Wrightia religiosa as tropical bonsai.
Indonesian bonsai artist, Kaima Towira, posted this picture, of a Wrightia recently dug from the ground. The Japanese general term for trees dug from the earth for bonsai is yamadori.
We often think of yamadori as pines and junipers, tropical plants are also collected "from the wild." As proof of Kaima's talent, one of a more "finished" bonsai is shown here on display at a bonsai exhibit.
Cliff Chong, in Malaysia, is the artist who created this tree. Pictures can be deceiving, this is not a large bonsai, but a beautiful shohin.
In Vietnam, Lam Ngoc Vinh creates both traditional and creatively unique bonsai using figurines.
The one shown here is "holding" a water jasmine.
Although rarely used in Japan, many other countries respect using figurines in their bonsai.
Carl Rosner, in New Jersey USA, enjoyed a wonderful experience with growing water jasmine as bonsai in his "Tree House." Over the years, Carl kept me posted on his bonsai. This one had very few problems - such as too many roots and a terrible attack of mites - which he quickly resolved.
Fast growing is the good news and the bad news. Frequent pruning of the foliage will keep it from getting too wild and hard branch pruning will add lots of ramification. This tree does not tolerate neglect.
The roots will also need pruning often. Check them once a year, but most likely will need pruning at least every two years. In the tropics, possibly more often.
If pruning the roots is neglected, you are asking for poor water drainage and potential weakening of the plant overall. Root pruning, as with most tropical bonsai, should be done during the time of warmest nights. Wrightia is considered a "heavy feeder," which means: do not neglect regular fertilizing.
Although it likes water, it can be over-watered. This will mainly depend on the type of soil and/or whether or not it is root bound. As with any bonsai, the bonsai soil should be fast draining. Over watering and under fertilizing can both contribute to yellow leaves.
Small branches are easily wired. Don't forget it grows fast and may cut in quickly. This tropical bonsai is susceptible to the same pests as many other tropical plants. Good light, air circulation and regular maintenance will prevent many of them.