Plant care
Silver Crowntemperature & humidity
Cotyledon undulata
More about silver crown
Ideal temperature for silver crown
Temperature kills fewer silver crown 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 7–27°C (45–81°F) is fine; the spot you put the plant in matters more. Below roughly 7°C the damage starts — soft blackened patches, translucent leaves, sometimes overnight.
Cold tolerance & winter care
Silver Crown is frost-tender (USDA 9b–11, RHS H1c). 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 silver crown
Silver Crown sits happiest at around 20–40% relative humidity. Prefers a dry atmosphere. The thick farinose coating is adapted to arid Western Cape conditions. High humidity encourages fungal problems, particularly if air movement is limited. Do not place near bathrooms or humidifiers. 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.
Silver Crown temperature & humidity — frequently asked questions
What temperature is best for silver crown?
Silver Crown grows best between 7–27°C (45–81°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 silver crown tolerate?
Silver Crown starts to suffer below roughly 7°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 silver crown need?
Silver Crown prefers about 20–40% relative humidity. Prefers a dry atmosphere. The thick farinose coating is adapted to arid Western Cape conditions. High humidity encourages fungal problems, particularly if air movement is limited. Do not place near bathrooms or humidifiers.
How do I raise humidity for silver crown?
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 silver crown live outside?
Silver Crown is rated for USDA zone 9b–11 and RHS hardiness H1c. Outside that range it must come indoors before the first frost — treat any outdoor stint as a summer holiday, not a permanent home.
More silver crown care
In the UK? Keeping silver crown warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full silver crown care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.