Plant care
Henderson's Allamandatemperature & humidity
Allamanda cathartica 'Hendersonii'
More about henderson's allamanda
Ideal temperature for henderson's allamanda
Temperature kills fewer henderson's allamanda plants than you'd think. What kills them is the micro-climate within a normal-temperature room — a leaf pressed against single-glazed winter glass, the hot dry updraft directly above a radiator, the cold blast from an AC vent. The thermostat reading at 15–32°C (59–90°F) is fine; the spot you put the plant in matters more. Below roughly 15°C the damage starts — soft blackened patches, translucent leaves, sometimes overnight.
Cold tolerance & winter care
Henderson's Allamanda is frost-tender (USDA 10-11, RHS H1b). 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 henderson's allamanda
Henderson's Allamanda sits happiest at around 50–80% relative humidity. Thrives in the high humidity of tropical and subtropical climates. When grown under glass, mist foliage in the morning during summer and ensure good ventilation to prevent fungal disease. In dry indoor conditions, place on a humidity tray or group with other plants. 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.
Henderson's Allamanda temperature & humidity — frequently asked questions
What temperature is best for henderson's allamanda?
Henderson's Allamanda grows best between 15–32°C (59–90°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 henderson's allamanda tolerate?
Henderson's Allamanda starts to suffer below roughly 15°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 henderson's allamanda need?
Henderson's Allamanda prefers about 50–80% relative humidity. Thrives in the high humidity of tropical and subtropical climates. When grown under glass, mist foliage in the morning during summer and ensure good ventilation to prevent fungal disease. In dry indoor conditions, place on a humidity tray or group with other plants.
How do I raise humidity for henderson's allamanda?
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 henderson's allamanda live outside?
Henderson's Allamanda is rated for USDA zone 10-11 and RHS hardiness H1b. Outside that range it must come indoors before the first frost — treat any outdoor stint as a summer holiday, not a permanent home.
More henderson's allamanda care
In the UK? Keeping henderson's allamanda warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full henderson's allamanda care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.