Averrhoa carambola or Carambola is a slow growing tree from the Malay Region. In nature, the trees will reach about 30 feet (9 m) tall and about half as wide. The alternate, odd-pinnate leaves are somewhat sensitive -- leaves fold together at night, much like mimosas. The trees produce a fruit known as a star fruit, which is an astringent fruit with a sweet and sour flavor. The slow growing nature of these trees makes them an excellent container tree. The trees are hardy in USDA zones 9-11.
Blooming: In the greenhouse, these plants start flowering in late spring and will have up to 4 flushes of flowers throughout the year. Flowers form in the leaf axils. The variegated white and purple flowers are followed by yellow to golden brown fruits that are up to 5 inches (12.7 cm) long.
Culture: Averrhoa carambola needs a rich, moist, slightly acidic soil mix with full sun to partial shade. In the greenhouse, we use a soil mix consisting of 2 parts peat moss to 1 part loam to 1 part sand or perlite. The ideal pH is 5.5 to 6.5. The trees are kept moist, but not overly wet, and fertilized weekly with a balanced fertilizer. Since they are very slow growers, careful pruning and re-potting is needed. Our trees at 5 years old are about 5 feet (1.5 m) tall. In the winter months, water is somewhat restricted, but the plants are never allowed to dry out. Plants are watered only enough to keep the foliage from shriveling.
Propagation: Averrhoa carambola is best propagated from seed.
Averrhoa carambola was featured as Plant of the Week June 17-23, 2005.
Guide to Past Plants-of-the-Week:
Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically the late Cal Lemke, who used to be OU's botany greenhouse grower and an avid gardener at home as well. If the above links don't work, then try the overview site. You may also like to look at the thumbnail index. ©1998-2012 All rights reserved.