Plant care
Kidney Vetchtemperature & humidity
Anthyllis vulneraria
More about kidney vetch
Ideal temperature for kidney vetch
Temperature kills fewer kidney vetch plants than you'd think. What kills them is the micro-climate within a normal-temperature room — a leaf pressed against single-glazed winter glass, the hot dry updraft directly above a radiator, the cold blast from an AC vent. The thermostat reading at -20 to 28°C (-4 to 82°F) is fine; the spot you put the plant in matters more. Below roughly -20°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Kidney Vetch is comparatively hardy (USDA 4-9, 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 kidney vetch
Kidney Vetch sits happiest at around Low relative humidity. Prefers the dry, open conditions of chalk downland and coastal clifftops; high ambient humidity in sheltered positions can encourage fungal issues on the woolly flower heads. 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.
Kidney Vetch temperature & humidity — frequently asked questions
What temperature is best for kidney vetch?
Kidney Vetch grows best between -20 to 28°C (-4 to 82°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 kidney vetch tolerate?
Kidney Vetch starts to suffer below roughly -20°C. It tolerates a cold dormant period within USDA 4-9, but a wet cold root zone is more dangerous than cold air.
What humidity does kidney vetch need?
Kidney Vetch prefers about Low relative humidity. Prefers the dry, open conditions of chalk downland and coastal clifftops; high ambient humidity in sheltered positions can encourage fungal issues on the woolly flower heads.
How do I raise humidity for kidney vetch?
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 kidney vetch live outside?
Kidney Vetch is rated for USDA zone 4-9 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 kidney vetch care
In the UK? Keeping kidney vetch warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full kidney vetch care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.