Cold hardiness & minimum temperature

Is Golden Trumpet (Allamanda cathartica)cold hardy? Hardiness zone & min temp

Also called Golden trumpet, Golden trumpet vine, Yellow allamanda, Yellow bell, Common allamanda.

More about golden trumpet

About Golden Trumpet

Allamanda cathartica · also called Golden trumpet, Golden trumpet vine · tropical

Golden trumpet is a fast-growing tropical evergreen vine prized for glossy leaves and large, waxy yellow trumpet flowers all summer. It demands full sun, warm humid air, and steady moisture in rich, free-draining soil. The milky sap irritates skin and eyes, and all parts are considered toxic if eaten, so keep it away from pets.

Cold limit: USDA USDA 10-11 (frost-tender; grown as a container or conservatory plant and overwintered indoors in cooler zones) (18-27 C)

Watch for — Leggy, sparse growth: Insufficient light plus lack of pruning. Cut back hard in late winter/early spring (by up to half) to force bushier growth and more flowering wood.

What golden trumpet's hardiness rating actually means

Golden Trumpet 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 USDA 10-11 (frost-tender; grown as a container or conservatory plant and overwintered indoors in cooler zones) — 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). Golden Trumpet has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for golden trumpet 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 golden trumpet 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 golden trumpet can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Golden Trumpet hardiness — frequently asked questions

Is golden trumpet cold hardy?

Golden Trumpet 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. Golden Trumpet can only live outside year-round in genuinely frost-free climates (roughly USDA USDA 10-11 (frost-tender; grown as a container or conservatory plant and overwintered indoors in cooler zones)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature golden trumpet can survive?

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

What hardiness zone is golden trumpet?

Golden Trumpet is rated USDA USDA 10-11 (frost-tender; grown as a container or conservatory plant and overwintered indoors in cooler zones) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can golden trumpet 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 golden trumpet 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.