UK temperature
Keeping moonstones warm in a UK home
Pachyphytum oviferum
More about moonstones in the UK
The UK home, in plant terms
A typical UK home creates two opposite micro-problems at the same time. Radiator-driven heating spikes the air temperature and crashes humidity in the rooms where people actually sit; the older the housing stock the more likely a single-glazed window pane is sitting at near-freezing in January with a houseplant against it. Cold unheated bedrooms, north-facing rooms and conservatories without heating run far cooler than the thermostat suggests, and the British winter gives the lowest indoor daylight in any of Growli's markets. Moonstones is frost-tender, so the radiator-warmed side of the house is right for it in winter — just not pressed against a cold pane or directly in the radiator updraft.
The actual numbers
Ideally moonstones sits between 18-27C ideal; keep above 7C (RHS H2: 1-5C minimum). (That is 65-80F ideal; keep above ~45F in Fahrenheit.) A dry-air desert succulent that is happy with normal, dry household humidity. Do not mist: water droplets sit on the leaves and permanently mar the protective farina coating. Good airflow helps prevent rot and fungal problems. Watch for the room dropping below about 18°C overnight — common in UK unheated bedrooms in January, and the point where growth stalls and leaves chill-mark.
For the RHS hardiness side of this, see is moonstones hardy in the UK? (rating RHS , sourced from the RHS rating system). For the US/USDA framing of the same numbers, see the moonstones temperature guide.
Winter placement in a UK home
For moonstones through a UK winter, three placement rules clear up most problems: 1) keep it at least a hand's width back from the window pane on single-glazed or very cold double-glazed glass, especially overnight when curtains close behind the plant; 2) keep it out of the direct vertical updraft above a radiator — that column of hot dry air browns leaf tips even on tolerant species; 3) judge by the room you can actually feel, not the central thermostat — many UK rooms run several degrees below the hall reading in winter. Humidity drops to roughly 25–35% in a heated UK living room; a pebble tray, grouping with other plants, or a small humidifier puts that back to a level houseplants actually like.
Moonstones temperature in the UK — frequently asked questions
What temperature does moonstones need in the UK?
Moonstones prefers 18-27C ideal; keep above 7C (RHS H2: 1-5C minimum) (65-80F ideal; keep above ~45F). The British issue is rarely the average — it is the extremes: a cold single-glazed window in January, the hot dry air directly above a radiator, or a north-facing unheated room that runs far cooler than the hall thermostat.
Will moonstones survive a cold UK winter room?
Moonstones is frost-tender (RHS undefined). Keep it well above freezing, ideally above 10°C overnight, which means the radiator-warmed side of the house rather than an unheated bedroom or conservatory.
Can moonstones go on a UK windowsill in winter?
On a single-glazed or very cold pane, no — overnight the leaves pressed against the glass can drop below the plant's comfort band, especially behind drawn curtains. A small gap (a hand's width back) or thicker thermal curtains in front of the plant fixes it, and modern double-glazing usually solves it outright.
Does UK radiator-driven heating dry moonstones out?
Yes — UK living rooms typically run at around 25–35% relative humidity in winter. That is well below what most houseplants prefer. Moonstones tolerates this better than the calathea-and-fern family, but a pebble tray or grouping plants still helps.
What temperature range does moonstones actually like?
18-27C ideal; keep above 7C (RHS H2: 1-5C minimum) is the comfortable band (65-80F ideal; keep above ~45F in Fahrenheit for reference). That covers normal UK living-room temperatures all year; the work is making sure cold pockets (windowsills, unheated rooms) and hot pockets (radiator updrafts) do not push it outside that band.
More moonstones care
See the full moonstones care guide, its UK watering (hard vs soft tap water), and UK hardiness.