Plant care
Kohlrabitemperature & humidity
Brassica oleracea var. gongylodes
More about kohlrabi
Ideal temperature for kohlrabi
Temperature kills fewer kohlrabi 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 15-24°C (60-75°F) is fine; the spot you put the plant in matters more. Below roughly 15°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Kohlrabi is comparatively hardy (USDA 3-11 (grown as a cool-season annual; tolerates light frost), RHS H4). 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 kohlrabi
Kohlrabi sits happiest at around Outdoor ambient relative humidity. An outdoor crop with no special humidity needs. It prefers cool growing conditions; hot, dry weather slows swelling and pushes plants to bolt before the bulb develops. 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.
Kohlrabi temperature & humidity — frequently asked questions
What temperature is best for kohlrabi?
Kohlrabi grows best between 15-24°C (60-75°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 kohlrabi tolerate?
Kohlrabi starts to suffer below roughly 15°C. It tolerates a cold dormant period within USDA 3-11 (grown as a cool-season annual; tolerates light frost), but a wet cold root zone is more dangerous than cold air.
What humidity does kohlrabi need?
Kohlrabi prefers about Outdoor ambient relative humidity. An outdoor crop with no special humidity needs. It prefers cool growing conditions; hot, dry weather slows swelling and pushes plants to bolt before the bulb develops.
How do I raise humidity for kohlrabi?
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 kohlrabi live outside?
Kohlrabi is rated for USDA zone 3-11 (grown as a cool-season annual; tolerates light frost) and RHS hardiness H4. 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 kohlrabi care
In the UK? Keeping kohlrabi warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full kohlrabi care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.