UK temperature
Keeping mustard greens 'red giant' warm in a UK home
Brassica juncea var. rugosa 'Red Giant'
More about mustard greens 'red giant' 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. Mustard Greens 'Red Giant' tolerates a wider band, but the worst-case UK winter placement (a cold single-glazed pane plus a hot dry radiator below it) still stresses it through repeated drying and chilling.
The actual numbers
Ideally mustard greens 'red giant' sits between 10-24°C. (That is 50-75°F in Fahrenheit.) Outdoor leafy crop governed by soil moisture, not air humidity. Space plants for airflow to reduce white blister and downy mildew on the broad leaves. Watch for the room dropping below about 10°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 mustard greens 'red giant' hardy in the UK? (rating RHS H5 (frost-hardy leaves; grown as an annual), sourced from the RHS rating system). For the US/USDA framing of the same numbers, see the mustard greens 'red giant' temperature guide.
Winter placement in a UK home
For mustard greens 'red giant' 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.
Mustard Greens 'Red Giant' temperature in the UK — frequently asked questions
What temperature does mustard greens 'red giant' need in the UK?
Mustard Greens 'Red Giant' prefers 10-24°C (50-75°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 mustard greens 'red giant' survive a cold UK winter room?
Mustard Greens 'Red Giant' tolerates a wider winter band — see its RHS rating H5 (frost-hardy leaves; grown as an annual). Below about 10°C growth stalls; cold-wet roots, not cold air, are usually what kills it indoors.
Can mustard greens 'red giant' 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 mustard greens 'red giant' out?
Yes — UK living rooms typically run at around 25–35% relative humidity in winter. That is well below what most houseplants prefer. Mustard Greens 'Red Giant' tolerates this better than the calathea-and-fern family, but a pebble tray or grouping plants still helps.
What temperature range does mustard greens 'red giant' actually like?
10-24°C is the comfortable band (50-75°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 mustard greens 'red giant' care
See the full mustard greens 'red giant' care guide, its UK watering (hard vs soft tap water), and UK hardiness.