Plant care
Bougainvilleatemperature & humidity
Bougainvillea glabra
More about bougainvillea
Ideal temperature for bougainvillea
Aim for 16-30 C ideal; keep above 10 C (60-85 F ideal; keep above 50 F) on the thermostat and you've handled the easy part. The hard part is the half-metre around the plant: window glass that drops to near-freezing on a January night, a radiator pumping out hot dry air, a draught from an opened front door. Move the plant 30 cm and you've usually fixed the problem. Below roughly 16°C the damage starts — soft blackened patches, translucent leaves, sometimes overnight.
Cold tolerance & winter care
Bougainvillea is frost-tender (USDA 9b-11 (grow in containers and overwinter indoors in cooler zones), RHS undefined). It cannot survive a frost, so in most of the US and UK it lives indoors year-round or summers outside and comes back in well before the first autumn frost — once nights drop toward 10-12°C is the cue, not the first frost warning. Acclimate it over a week when moving between indoors and out so the leaves do not shock.
Humidity for bougainvillea
Bougainvillea sits happiest at around Average; 40-60% relative humidity. Adaptable to ordinary household and garden humidity. RHS notes higher humidity in bright spring periods can encourage bud break, but soggy, stagnant air invites fungal leaf spot, so prioritise airflow over misting. The usual low-humidity tell is crisp brown leaf tips and edges while the soil moisture is fine — a sign the air, not the watering, is the problem. If you need to raise it, the reliable methods are grouping plants together, standing the pot on a tray of damp pebbles (the pot above the waterline, never in it), or running a small humidifier in winter when indoor heating dries the air most. Misting is the least effective — it raises humidity for minutes, not hours.
Bougainvillea temperature & humidity — frequently asked questions
What temperature is best for bougainvillea?
Bougainvillea grows best between 16-30 C ideal; keep above 10 C (60-85 F ideal; keep above 50 F). Keep it out of cold draughts, off freezing windowsills in winter, and away from the hot dry air directly above radiators — the extremes matter far more than the average room temperature.
How cold can bougainvillea tolerate?
Bougainvillea starts to suffer below roughly 16°C. It is frost-tender and will be damaged or killed by a frost, so bring it indoors once nights fall toward 10-12°C.
What humidity does bougainvillea need?
Bougainvillea prefers about Average; 40-60% relative humidity. Adaptable to ordinary household and garden humidity. RHS notes higher humidity in bright spring periods can encourage bud break, but soggy, stagnant air invites fungal leaf spot, so prioritise airflow over misting.
How do I raise humidity for bougainvillea?
Group it with other plants, stand the pot on a tray of damp pebbles (kept above the waterline), or run a small humidifier in winter. Misting only helps for a few minutes, so it is the weakest option for a plant that genuinely needs more humidity.
Can bougainvillea live outside?
Bougainvillea is rated for USDA zone 9b-11 (grow in containers and overwinter indoors in cooler zones). Outside that range it must come indoors before the first frost — treat any outdoor stint as a summer holiday, not a permanent home.
More bougainvillea care
In the UK? Keeping bougainvillea warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full bougainvillea care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.