Cold hardiness & minimum temperature

Is Butt's bougainvillea (Bougainvillea x buttiana)cold hardy? Hardiness zone & min temp

Also called Butt's bougainvillea, Buttiana bougainvillea.

More about butt's bougainvillea

About Butt's bougainvillea

Bougainvillea x buttiana · also called Butt's bougainvillea, Buttiana bougainvillea · tropical

Bougainvillea x buttiana is the primary interspecific hybrid (B. glabra × B. peruviana) that gave rise to most modern cultivars, including the classic 'Mrs Butt' with its crimson bracts. It is vigorous, adaptable, and widely used for warm-climate screening, pergola coverage, and container displays requiring hot colour from spring through autumn.

Cold limit: USDA 10–12 · RHS H1b (10°C to 42°C)

Watch for — Frost damage: Foliage blackens after even light frost (below 4 °C / 39 °F). In temperate climates, move containers under glass before first frost. Established plants in sheltered UK spots may resprout from the base after a mild frost but are reliably hardy only above 10 °C.

What butt's bougainvillea's hardiness rating actually means

Butt's bougainvillea 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 10–12 — 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 10 °C (sustained cold below this is damaging). Butt's bougainvillea has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Butt's bougainvillea hardiness — frequently asked questions

Is butt's bougainvillea cold hardy?

Butt's bougainvillea 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. Butt's bougainvillea 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 butt's bougainvillea can survive?

What hardiness zone is butt's bougainvillea?

Butt's bougainvillea is rated USDA 10–12 and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can butt's bougainvillea 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 butt's bougainvillea 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.