Plant care
Hardy Ice Planttemperature & humidity
Delosperma cooperi
More about hardy ice plant
Ideal temperature for hardy ice plant
Temperature kills fewer hardy ice plant 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 -15–35°C (5–95°F) is fine; the spot you put the plant in matters more. Below roughly -15°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Hardy Ice Plant is comparatively hardy (USDA 6–10, RHS H4). Within that range it tolerates a cold dormant spell outdoors; outside it, grow it in a container you can move under cover or overwinter in a cool but frost-free spot. Hardiness assumes an established plant in well-drained soil — a wet, cold root zone kills far more plants than cold air alone.
Humidity for hardy ice plant
Hardy Ice Plant sits happiest at around Low, 20–40% RH relative humidity. Adapted to the dry, arid conditions of its native South African habitat. Dislikes prolonged humid or damp conditions, especially in winter. Good air circulation and exposed, sunny positions prevent the wet crown conditions that lead to rot. 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.
Hardy Ice Plant temperature & humidity — frequently asked questions
What temperature is best for hardy ice plant?
Hardy Ice Plant grows best between -15–35°C (5–95°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 hardy ice plant tolerate?
Hardy Ice Plant starts to suffer below roughly -15°C. It tolerates a cold dormant period within USDA 6–10, but a wet cold root zone is more dangerous than cold air.
What humidity does hardy ice plant need?
Hardy Ice Plant prefers about Low, 20–40% RH relative humidity. Adapted to the dry, arid conditions of its native South African habitat. Dislikes prolonged humid or damp conditions, especially in winter. Good air circulation and exposed, sunny positions prevent the wet crown conditions that lead to rot.
How do I raise humidity for hardy ice plant?
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 hardy ice plant live outside?
Hardy Ice Plant is rated for USDA zone 6–10 and RHS hardiness H4. Within that range it can stay outdoors; outside it, grow it in a moveable container and protect the roots from a wet, cold winter.
More hardy ice plant care
In the UK? Keeping hardy ice plant warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full hardy ice plant care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.