Cold hardiness & minimum temperature

Is Bilimbi (Averrhoa bilimbi)cold hardy? Hardiness zone & min temp

Also called Bilimbi, Cucumber tree, Tree sorrel.

More about bilimbi

About Bilimbi

Averrhoa bilimbi · also called Bilimbi, Cucumber tree · tropical

Bilimbi is a tropical evergreen tree, a close relative of starfruit, that bears clusters of small, intensely sour green fruit directly on its trunk and branches. Grown across Southeast Asia for cooking, pickling and drinks, it needs hot, humid, frost-free conditions. The very acidic fruit is rich in oxalic acid, making it hazardous to pets and to people with kidney issues.

Cold limit: USDA 10-11 (very frost-tender; even less cold-hardy than carambola) · RHS H1b (22-32°C)

Watch for — Cold and frost damage: Extremely frost-tender; even brief cold defoliates or kills the tree, so it needs reliably warm, sheltered sites or greenhouse protection.

What bilimbi's hardiness rating actually means

Bilimbi 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 H1b means: Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season. On the US scale that maps to USDA 10-11 (very frost-tender; even less cold-hardy than carambola) — 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 10 °C (sustained cold below this is damaging). Bilimbi has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for bilimbi as it gets too cold:

Below about about 10 °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 bilimbi go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 10 °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 bilimbi can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Bilimbi hardiness — frequently asked questions

Is bilimbi cold hardy?

Bilimbi 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. Bilimbi can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (very frost-tender; even less cold-hardy than carambola)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature bilimbi can survive?

Minimum survivable temperature is roughly about 10 °C (sustained cold below this is damaging). Bilimbi has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is bilimbi?

Bilimbi is rated USDA 10-11 (very frost-tender; even less cold-hardy than carambola) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can bilimbi survive winter outside?

It can holiday outdoors in summer once nights are reliably above 10 °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 bilimbi below its minimum temperature?

Below about about 10 °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.