Cold hardiness & minimum temperature

Is Yellow Trumpetbush (Tecoma stans)cold hardy? Hardiness zone & min temp

Also called Yellow Trumpetbush, Yellow Elder, Yellow Bells, Esperanza, Trumpetbush.

More about yellow trumpetbush

About Yellow Trumpetbush

Tecoma stans · also called Yellow Trumpetbush, Yellow Elder · tropical

A fast-growing evergreen shrub or small tree bearing clusters of bright yellow trumpet flowers nearly year-round in frost-free climates. Thrives in full sun with well-drained soil and excellent drought tolerance once established. Ideal for warm gardens, poolsides, and large containers. Best in USDA zones 9–11; bring under glass in cooler regions.

Cold limit: USDA 9-11 · RHS H1c (10–38°C (growing); minimum -4°C briefly for established plants)

What yellow trumpetbush's hardiness rating actually means

Yellow Trumpetbush 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 9-11 — 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). Yellow Trumpetbush has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Yellow Trumpetbush hardiness — frequently asked questions

Is yellow trumpetbush cold hardy?

Yellow Trumpetbush 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. Yellow Trumpetbush can only live outside year-round in genuinely frost-free climates (roughly USDA 9-11); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature yellow trumpetbush can survive?

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

What hardiness zone is yellow trumpetbush?

Yellow Trumpetbush is rated USDA 9-11 and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can yellow trumpetbush 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 yellow trumpetbush 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.