Plant care
Gardeniatemperature & humidity
Gardenia jasminoides
More about gardenia
Ideal temperature for gardenia
Aim for 16-24°C (60-75°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
Gardenia is frost-tender (USDA 7b-11b (most cultivars; hardy selections like 'Kleim's Hardy' tolerate down to about -12°C / 10°F), RHS H1C (tender; can stand outside in summer but needs a minimum of 5-10°C and frost-free protection over winter)). 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 gardenia
Gardenia sits happiest at around 50-70% relative humidity. Gardenias demand high humidity and resent dry centrally-heated air, which is a frequent cause of indoor bud drop. Stand the pot on a tray of damp pebbles (base above the waterline) or run a humidifier nearby. Grouping plants together also raises local moisture. 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.
Gardenia temperature & humidity — frequently asked questions
What temperature is best for gardenia?
Gardenia grows best between 16-24°C (60-75°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 gardenia tolerate?
Gardenia 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 gardenia need?
Gardenia prefers about 50-70% relative humidity. Gardenias demand high humidity and resent dry centrally-heated air, which is a frequent cause of indoor bud drop. Stand the pot on a tray of damp pebbles (base above the waterline) or run a humidifier nearby. Grouping plants together also raises local moisture.
How do I raise humidity for gardenia?
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 gardenia live outside?
Gardenia is rated for USDA zone 7b-11b (most cultivars; hardy selections like 'Kleim's Hardy' tolerate down to about -12°C / 10°F) and RHS hardiness H1C (tender; can stand outside in summer but needs a minimum of 5-10°C and frost-free protection over winter). Outside that range it must come indoors before the first frost — treat any outdoor stint as a summer holiday, not a permanent home.
More gardenia care
In the UK? Keeping gardenia warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full gardenia care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.