Cold hardiness & minimum temperature

Is Cashew (Anacardium occidentale)cold hardy? Hardiness zone & min temp

Also called cashew, cashew apple tree.

More about cashew

About Cashew

Anacardium occidentale · also called cashew, cashew apple tree · edible

Cashew is a spreading tropical evergreen tree producing a swollen, juicy cashew apple topped by the kidney-shaped nut. The raw nutshell contains caustic urushiol-type oils (it is a poison-ivy relative), so nuts must be roasted before eating. Fast-growing, drought-tolerant once established and frost-tender, it is a productive lowland tropical orchard tree.

Cold limit: USDA 10-11 (tropical/subtropical; frost-tender) · RHS H1b (20-35°C)

Watch for — Frost damage: Frost-tender and intolerant of cold; even a light frost kills young trees. It can only be grown outdoors in frost-free tropical or subtropical zones.

What cashew's hardiness rating actually means

Cashew 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 (tropical/subtropical; frost-tender) — 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). Cashew has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for cashew 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 cashew 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 cashew can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Cashew hardiness — frequently asked questions

Is cashew cold hardy?

Cashew 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. Cashew can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (tropical/subtropical; frost-tender)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature cashew can survive?

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

What hardiness zone is cashew?

Cashew is rated USDA 10-11 (tropical/subtropical; frost-tender) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can cashew 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 cashew 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.