UK temperature
Keeping calathea 'flamestar' warm in a UK home
Goeppertia veitchiana 'Flamestar'
More about calathea 'flamestar' 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. Calathea 'Flamestar' 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 calathea 'flamestar' sits between 18-27 C (ideal 18-24 C); avoid below 15 C. (That is 64-81 F (ideal 64-75 F); avoid below 59 F in Fahrenheit.) High humidity is the make-or-break factor. In dry household air the wavy leaf edges turn brown and brittle. Raise humidity with a humidifier, a pebble-and-water tray or by grouping with other plants. Misting helps temporarily but a humidifier is far more reliable. 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 calathea 'flamestar' hardy in the UK? (rating RHS , sourced from the RHS rating system). For the US/USDA framing of the same numbers, see the calathea 'flamestar' temperature guide.
Winter placement in a UK home
For calathea 'flamestar' 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.
Calathea 'Flamestar' temperature in the UK — frequently asked questions
What temperature does calathea 'flamestar' need in the UK?
Calathea 'Flamestar' prefers 18-27 C (ideal 18-24 C); avoid below 15 C (64-81 F (ideal 64-75 F); avoid below 59 F). 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 calathea 'flamestar' survive a cold UK winter room?
Calathea 'Flamestar' 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 calathea 'flamestar' 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 calathea 'flamestar' out?
Yes — UK living rooms typically run at around 25–35% relative humidity in winter. That is well below what most houseplants prefer. Calathea 'Flamestar' is in the high-humidity group, so a pebble tray, grouping with other plants, or a small humidifier is genuinely needed through the heating season.
What temperature range does calathea 'flamestar' actually like?
18-27 C (ideal 18-24 C); avoid below 15 C is the comfortable band (64-81 F (ideal 64-75 F); avoid below 59 F 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 calathea 'flamestar' care
See the full calathea 'flamestar' care guide, its UK watering (hard vs soft tap water), and UK hardiness.