Plant care
Longantemperature & humidity
Nephelium longana
More about longan
Ideal temperature for longan
Aim for 15–35°C (59–95°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 15°C the damage starts — soft blackened patches, translucent leaves, sometimes overnight.
Cold tolerance & winter care
Longan is frost-tender (USDA 9b–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 longan
Longan sits happiest at around 50–80% relative humidity. Tolerates a moderately broad humidity range. Thrives in the warm, humid tropics but adapts reasonably well to drier subtropical summers provided irrigation compensates. Very low winter humidity combined with cold can damage buds. Avoid extended periods below 40% humidity in hot weather. 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.
Longan temperature & humidity — frequently asked questions
What temperature is best for longan?
Longan grows best between 15–35°C (59–95°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 longan tolerate?
Longan 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 longan need?
Longan prefers about 50–80% relative humidity. Tolerates a moderately broad humidity range. Thrives in the warm, humid tropics but adapts reasonably well to drier subtropical summers provided irrigation compensates. Very low winter humidity combined with cold can damage buds. Avoid extended periods below 40% humidity in hot weather.
How do I raise humidity for longan?
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 longan live outside?
Longan is rated for USDA zone 9b–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 longan care
In the UK? Keeping longan warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full longan care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.