Cold hardiness & minimum temperature

Is Carambola Star Fruit (Averrhoa carambola)cold hardy? Hardiness zone & min temp

Also called Star Fruit, Five-Corner Fruit, Belimbing.

More about carambola star fruit

About Carambola Star Fruit

Averrhoa carambola · also called Star Fruit, Five-Corner Fruit · edible

Carambola is a tropical fruit tree producing distinctive five-ribbed, waxy fruits with a sweet-tart flavour. It is attractive as both a garden tree and container specimen. Fruits are rich in vitamin C. Star fruit contains oxalates that are dangerous to people with kidney disease and can be harmful to cats and dogs; classified as toxic.

Cold limit: USDA 10-12 · RHS H1B (20-35°C)

Watch for — Fruit drop after flowering: Low potassium, drought stress, or cold nights can cause premature drop. Consistent fertilising and irrigation during fruit set helps.

What carambola star fruit's hardiness rating actually means

Carambola Star Fruit is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Its RHS rating of H1c means: Warm-temperate — can summer outdoors but must come in well before the first frost. On the US scale that maps to USDA 10-12 — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly about 5 °C (and never frost). Carambola Star Fruit has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for carambola star fruit as it gets too cold:

Below about about 5 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches.
A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover.
Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.

Can carambola star fruit go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 5 °C, in shade or dappled light, hardened off gradually.
Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C.
It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when carambola star fruit can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Carambola Star Fruit hardiness — frequently asked questions

Is carambola star fruit cold hardy?

Carambola Star Fruit is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Indoor-only in almost every home. Carambola Star Fruit can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature carambola star fruit can survive?

Minimum survivable temperature is roughly about 5 °C (and never frost). Carambola Star Fruit has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is carambola star fruit?

Carambola Star Fruit is rated USDA 10-12 and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can carambola star fruit survive winter outside?

It can holiday outdoors in summer once nights are reliably above 5 °C, in shade or dappled light, hardened off gradually. Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C. It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

What happens to carambola star fruit below its minimum temperature?

Below about about 5 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches. A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover. Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.