Starfruit

Tree facts

Scientific name

Averrhoa carambola

Origin

Southeast Asia (Sri Lanka and the Moluccas)

Tree size

20–30 ft if left alone; easily kept at 10–15 ft

Growth rate

Medium

Sun

Full sun

Soil

Well-drained soil. On limestone and alkaline soils it often needs iron, zinc and manganese sprays.

Soil pH

5.5–6.5

Pollination

Many cultivars set fruit alone, but planting two cultivars improves crops

Cold hardiness

Young trees are damaged near 32°F; mature trees take brief dips to about 27–29°F

USDA zones

9b–11

Years to first fruit

1–3 for a grafted tree

Season

Aug–Feb

Water

About every 7 days once established, without rain; more in heat, in pots and while young

Feeding

About every 90 days, Mar–Sep

Pruning

Mar–Apr

Taste

Crisp, juicy and sweet-tart, like a mix of apple, grape and citrus

Nutrition

Good source of vitamin C and fiber; low in calories. Also high in oxalic acid.

Is starfruit safe to eat? Edible and toxic parts

What you can eat

• Ripe fruit, raw or cooked, skin and all
• Green or tart fruit, cooked into relishes and pickles

Toxic parts and cautions

• Toxic: Never eat starfruit if you have kidney disease or reduced kidney function. It contains caramboxin, a neurotoxin that failing kidneys can't clear, and it has caused hiccups, confusion, seizures and deaths even after one or two fruit.
• Take care: Starfruit is high in oxalate. Large amounts, especially sour juice on an empty stomach, have caused kidney injury in people with healthy kidneys. Enjoy it in normal servings.
• Good to know: Like grapefruit, starfruit may interfere with how some medicines are broken down. Check with a pharmacist if you take prescription drugs.

Pets: Toxic to dogs, cats and horses: its soluble oxalates can cause low calcium and kidney damage. Pick up fallen fruit.

How to eat and enjoy starfruit

• Fresh, sliced into stars for salads and garnishes
• Juice and agua fresca
• Chutneys, relishes and pickles from tart fruit
• Dried star chips

Starfruit varieties (7)

• Arkin

  The leading Florida starfruit: sweet, juicy, bright yellow-orange fruit that ships well.

  Origin: Florida, 1973 · Taste: Sweet, mild · Size: Medium to large

• B-10

  A large, sweet Malaysian commercial starfruit.

  Origin: Malaysia · Taste: Sweet · Size: Large

• B-17

  A Malaysian starfruit known for very sweet, crisp fruit.

  Origin: Malaysia · Taste: Very sweet, crisp · Size: Large

• Fwang Tung

  A large, sweet Thai starfruit with deep ribs that make sharp star-shaped slices.

  Origin: Thailand · Taste: Sweet, mild · Size: Large

• Golden Star

  An older Florida starfruit with deep wings. It's tart until fully ripe, then sweet-tart.

  Origin: Florida · Taste: Sweet-tart

• Kary

  A sweet Hawaiian starfruit with golden-yellow fruit.

  Origin: Hawaii · Taste: Sweet

• Sri Kembangan · also Kembangan

  A sweet, juicy Malaysian starfruit with long, orange-yellow fruit.

  Origin: Malaysia · Taste: Sweet, juicy · Size: Large

Pests and diseases to watch for

• Anthracnose

  Black, sunken spots on flowers, young leaves and fruit; blossoms turn black and drop. Ripe fruit gets dark spots that spread and rot.

  What to do: Prune out dead twigs and blackened panicles.

• Caribbean fruit fly

  Ripe fruit with tiny puncture marks; maggots inside and soft, rotting spots.

  What to do: Pick fruit slightly early and ripen indoors.

• Scale insects

  Small bumps, waxy or shell-like, on stems and leaf veins; sticky honeydew and black sooty mold below.

  What to do: Scrub small colonies off with a soft brush.

• Mealybugs

  White cottony clusters in leaf joints, under leaves and on fruit stems; honeydew and sooty mold.

  What to do: Blast off with a strong spray of water.

• Aphids

  Clusters of tiny soft insects on new shoots; leaves curl and get sticky.

  What to do: Spray off with water.

• Sooty mold

  Black, papery film on leaves and fruit that wipes off; it grows on honeydew.

  What to do: Control the insects making honeydew; the mold then weathers away.