Some fruits are either feast or famine and the star fruit is one of those wonders. This fall, not only was our starfruit at the East Port Environmental Campus Demonstration Garden producing, several Master Gardeners were also bringing in bags of extra fruit to share – nice! Whether you call it carambola, star fruit or five-finger, the fruit tree known scientifically as Averrhoa carambola is exotic, tasty, and makes a nice ornamental yard tree. Why not try this tree fruit in your own back yard?
First, let me quote word for word from our UF/IFAS publication, "People who have been diagnosed with kidney disease should not eat carambola (star fruit) unless their doctor says it is safe for them to eat. This fruit may contain enough oxalic acid to cause a rapid decline in renal function." Please keep this important warning in mind. Originally from Southeast Asia, the carambola has been grown in Florida for over one hundred years and is commercially produced in Dade, Lee, Broward, and Palm Beach counties. This fruit is commonly seen in produce departments in most grocery stores and is familiar to almost everyone. The carambola tree is small to medium in size, evergreen to semi-evergreen depending on winter temperatures and may have a single or multiple trunks. The small, but colorful pink to lavender flowers are about three-eighths of an inch long. The flowers are followed by a fleshy waxy berry from two to six-inches long with five lobbed ribs that appear star-shaped when cut in cross-section. It takes about seventy-five days from the time the fruit sets until it is ready to pick. There are also about twelve edible seeds per fruit. Carambolas really appreciate being protected from windy sites. As a matter of fact, wind damaged trees will show browning or distorted leaves, some stem dieback, fruit damage and general stunted growth. Keeping carambola trees pruned to about twelve feet tall will also help increase hurricane resistance. Select a site to plant your carambola that is in full sun, out of the wind and is well drained. If necessary, plant the tree on a mound of soil to raise it up above areas that sometimes flood. Build the mound three to four foot high and four to ten feet wide using native soil. Carambolas are not tolerant of salty conditions and also may show nutrient deficiencies in high pH soils. As the tree matures, it tolerance to cold and freezing will improve. Generally, at temperatures of twenty to twenty-four degrees Fahrenheit, large branches and even mature trees may die. Accordingly, some protection may be necessary during the coldest of our winter weather.
Carambola normally have two major crops per year ready from August through September and from December through February. There will also be scattered smaller crops. A five year old tree can produce up to one hundred pounds per tree. Mature trees can eventually supply you with over two-hundred and fifty pounds a year. It is no wonder why carambola tree owners are always giving fruit away to friends and neighbors! A complete fertilizer suitable for tropical fruits used as per label directions will keep the tree productive and healthy. In addition, foliar applications of micronutrients may be needed to ward off deficiencies. Variety selection is as much an issue of what is available in the local garden centers, and what your personal tastes are. Carambolas are either sweet or tart - some tart varieties will even sweeten up if left on the tree to ripen further. ‘Arkin’ is a cultivar that originated in Florida, has a sweet flavor and is very well suited for backyard production. ‘Lara’ is another variety from Florida that is also sometimes available. ‘Fwang Tung’ is also recommended. Local box store garden centers and specialty nurseries regularly carry carambola. Carambola is a great dooryard fruit tree that is easy to grow and produces an abundance of tasty fruit. Perhaps give one as a gift to someone this Holiday Season! For more information on all types of fruit to grow in our area, please call our Master Gardener volunteers on the Plant Lifeline on Mondays, Wednesdays and Fridays from 1 to 4 pm at 764-4340 for gardening help and insight into their role as an Extension volunteer. Don't forget to visit our other County Plant Clinics in the area. Please check this link for a complete list of site locations, dates and times - http://charlotte.ifas.ufl.edu/horticulture/Plant%20Clinics%20Schedule.pdf.
Resource: Crane, J. H. (2013) Carambola Growing in the Florida Home Landscape. The University of Florida Extension Service, IFAS.