Plant care
Lemon Thymetemperature & humidity
Thymus citriodorus
More about lemon thyme
Ideal temperature for lemon thyme
Aim for 10-26°C (50-79°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 10°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Lemon Thyme is comparatively hardy (USDA 5-9, 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 lemon thyme
Lemon Thyme sits happiest at around 30-50% relative humidity. Prefers dry air and good airflow, reflecting its Mediterranean origins. High humidity and crowding encourage fungal problems and root rot, so keep it airy and on the dry side. 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.
Lemon Thyme temperature & humidity — frequently asked questions
What temperature is best for lemon thyme?
Lemon Thyme grows best between 10-26°C (50-79°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 lemon thyme tolerate?
Lemon Thyme starts to suffer below roughly 10°C. It tolerates a cold dormant period within USDA 5-9, but a wet cold root zone is more dangerous than cold air.
What humidity does lemon thyme need?
Lemon Thyme prefers about 30-50% relative humidity. Prefers dry air and good airflow, reflecting its Mediterranean origins. High humidity and crowding encourage fungal problems and root rot, so keep it airy and on the dry side.
How do I raise humidity for lemon thyme?
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 lemon thyme live outside?
Lemon Thyme is rated for USDA zone 5-9 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 lemon thyme care
In the UK? Keeping lemon thyme warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full lemon thyme care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.