Plant care
Wall Ruetemperature & humidity
Asplenium ruta-muraria
More about wall rue
Ideal temperature for wall rue
Wall Rue is comfortable in any room a person is comfortable in, roughly -10-22°C (14-72°F). The mistakes are micro-climates: a north-facing window on a frosty night, a south-facing windowsill in a summer heatwave, the standing draught between an opened kitchen door and the radiator behind it. Read the room around the plant, not the thermostat. Below roughly -10°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Wall Rue is comparatively hardy (USDA 5-8, 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 wall rue
Wall Rue sits happiest at around 40-60% relative humidity. Tolerates relatively low ambient humidity better than most ferns, surviving on exposed walls. Moderate moisture in the air suits it but it does not require a humid micro-climate. 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.
Wall Rue temperature & humidity — frequently asked questions
What temperature is best for wall rue?
Wall Rue grows best between -10-22°C (14-72°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 wall rue tolerate?
Wall Rue starts to suffer below roughly -10°C. It tolerates a cold dormant period within USDA 5-8, but a wet cold root zone is more dangerous than cold air.
What humidity does wall rue need?
Wall Rue prefers about 40-60% relative humidity. Tolerates relatively low ambient humidity better than most ferns, surviving on exposed walls. Moderate moisture in the air suits it but it does not require a humid micro-climate.
How do I raise humidity for wall rue?
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 wall rue live outside?
Wall Rue is rated for USDA zone 5-8 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 wall rue care
In the UK? Keeping wall rue warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full wall rue care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.