Carambola (known botanically as Averrhoa carambola) is a rising star in the world of tropical fruit. It's reliably hardy only in south Florida, but its unique yellow fruits are popular in supermarkets throughout the South: Peeling isn't necessary, and the flavorful slices can be added to fruit salads, floated in bowls of punch, or enjoyed as a dessert.
Native to Sri Lanka and Southeast Asia, carambola is a slow-growing evergreen tree with a short trunk and a broad, rounded canopy, reaching 2530 ft. tall and wide at maturity. Leaves are arranged spirally on the branches; they are medium green, 610 in. long, each with 5 to 11 ovate leaflets. Clusters of fragrant pink-to-lavender flowers appear in several flushes throughout the year; they are followed by oval, pointed, waxy-skinned, juicy yellow fruits, 46 in. long, with five prominent longitudinal ribs. Cutting the fruit crosswise produces star-shaped slices. Some compare the flavor to mild citrus, while others call it a blend of pineapple, apple, and citrus. Overall, it may be sweet or rather sour; named selections are usually sweet. Some selections are self-fertile, while others need cross-pollination with another selection to bear fruit.
Carambola is popular as a small shade tree in south Florida. Careful siting is necessary, however, because grass will not grow beneath the dense canopy.
Recommended selections include the following.
'Arkin'. Bright yellow to yellow-orange fruit, 45 in. long; firm and very sweet, with few seeds. Keeps well. Self-fertile but bears better with a pollenizer.
'Fwang Tung'. Pale yellow, 5- to 6-in.-long fruit is firm and very sweet, with few seeds. Self-fertile.
'Golden Star'. Originated in Homestead, Florida, in the 1940s. Golden yellow fruit with very waxy skin; 56 in. long, crisp and mildly sweet. Self-fertile.
'Lara'. Fruit is 45 in. long; dark yellow to orange. Sweet flavor. Self-fertile
'Maher Dwarf'. Hawaiian selection that grows just 24 ft. tall in a container. Begins bearing roundish fruit when just 1 ft. tall. Sweet and crunchy. Self-fertile.
'Sri Kembanqan' ('Sri Kembangan'). Firm, bright yellow-orange, 5- to 6-in.-long fruit with few seeds. Rich, sweet flavor; excellent dessert quality. Needs a pollenizer.
Although carambola briefly tolerates temperatures as low as 27F, it really is best planted in frost-free locations. The soil should be well drained and moderately acid (pH 5.56.5); chlorosis (yellow leaves with green veins) often occurs in alkaline soil. Fertile soil containing lots of organic matter results in faster growth and more fruit. The tree is quite susceptible to drought, so water it regularly during dry periods, even in winter. Fertilize two or three times a year during periods of active growth with an appropriate fruit-tree fertilizer. Full sun is a must. Pruning is rarely necessary, and pests are seldom serious.