A member of the Oxalidaceae (Wood Sorrel) family, the Averrhoa genus contains two species,
both of which are cultivated for edible fruit. Averrhoa carambola, known as the Starfruit or Carambola tree,
is more cold-hardy and tolerant of dryer soils.
Form: Short trunked, multi-branched tree.
Lifespan: 25-50 years.
Leaf retention: Deciduous in low, near freezing temperatures.
Evergreen in regions without freezes.
Growth rate: Slow.
Mature Size: 25-30' high and 20-25' wide.
Flowers: Small, pink to purple, five petals, fragrant, clustered.
Bloom: 2-4 times a year in regions without freezes.
Years before fruiting: 1-4 if grafted, 3-5 from seed.
Fruit: Yellow, waxy skin, usually five longitudinal ribs (can be 4-8),
star-shaped cross section. Dark yellow, translucent, juicy flesh with 0-12 edible seeds. The flavor
varies from very sour (high oxalic acid) to mildly sweet.
Months for fruit to ripen: 2-3. Ripe when fully colored and ribs
are beginning to turn brown. Does not ripen off the tree.
Storage after harvest: One week at room temperature.
Leaves: Green, grouped as 5-11 leaflets, tend to fold at night or
Stems: No thorns.
Roots: Not invasive in dry climates.
Cultivars of Note:
'Arkin' Medium to large fruit, sweet, good flavor,
self-pollinating, the leading commercial cultivar, created in Florida.
'Fwang Tung' Medium to large fruit, sweet, very good flavor,
self-pollinating, from Thailand.
'Kary' Medium to large fruit, sweet, very good flavor,
'Sri Kembangan' Large fruit, sweet, good flavor,
self-pollinating, from Thailand.
Wildlife: Attracts bees, moths.
Toxic / Danger: The fruit contains oxalic acid, and sour fruit
varieties have high amounts. This can be dangerous for those with kidney disease.
Origin: Southeast Asia.
Cultivation and Uses
USDA hardiness zones: 10-13. Protect from freezing temperatures.
Chill hours: None.
Heat tolerant: All day part shade and extra water needed above 95°F.
Sun: Full sun to part shade.
Drought tolerant: No.
Water after becoming established: 2-3 times a week to avoid dry soil,
even in the winter. Not tolerant of flooding.
Soil: Well drained, best in moist, moderate to high organic content,
pH 4.5-7.0 (strongly acidic to neutral). Not tolerant of alkaline or saline soil.
Fertilize: One or two applications a year of composted manure and mulch.
Apply citrus micronutrients once a year. This plant is prone to chlorosis, which can be
treated with chelated iron. If the chlorosis occurs in winter, it will often disappear on
its own in warmer weather.
Mulch: Place organic material under the canopy, 2-6" thick, 8-12" from
the trunk, to reduce moisture loss.
Spacing: 15-20' between plants.
Planting: Dwarf varieties can be grown in containers.
First Year Care: Protect from freezing temperatures.
Prune: Prune to shape and size in mid winter. Flowers occur on both
old and new wood.
Litter: Low except for unharvested fruit or dropped leaves in cold
Propagation: Grafted buds or shoots onto hardy rootstock. Seed does
not breed true but can be used for rootstock.
Uses: Fruit tree.
Another common name is Carambola tree.
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