Plant care
Red Campiontemperature & humidity
Silene dioica
More about red campion
Ideal temperature for red campion
Aim for -20 to 25°C (-4 to 77°F) on the thermostat and you've handled the easy part. The hard part is the half-metre around the plant: window glass that drops to near-freezing on a January night, a radiator pumping out hot dry air, a draught from an opened front door. Move the plant 30 cm and you've usually fixed the problem. Below roughly -20°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Red Campion is comparatively hardy (USDA 4-8, RHS H6). 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 red campion
Red Campion sits happiest at around Ambient relative humidity. No special humidity requirement; the plant grows well under typical UK outdoor conditions, preferring sheltered positions away from desiccating winds. 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.
Red Campion temperature & humidity — frequently asked questions
What temperature is best for red campion?
Red Campion grows best between -20 to 25°C (-4 to 77°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 red campion tolerate?
Red Campion starts to suffer below roughly -20°C. It tolerates a cold dormant period within USDA 4-8, but a wet cold root zone is more dangerous than cold air.
What humidity does red campion need?
Red Campion prefers about Ambient relative humidity. No special humidity requirement; the plant grows well under typical UK outdoor conditions, preferring sheltered positions away from desiccating winds.
How do I raise humidity for red campion?
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 red campion live outside?
Red Campion is rated for USDA zone 4-8 and RHS hardiness H6. 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 red campion care
In the UK? Keeping red campion warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full red campion care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.