Plant care
Field marigoldtemperature & humidity
Calendula arvensis
More about field marigold
Ideal temperature for field marigold
Aim for 7–20 °C optimal; tolerates light frost to −5 °C (45–68 °F optimal; tolerates light frost to 23 °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 7°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Field marigold is comparatively hardy (USDA 6–10 (cool-season annual; self-seeds in zones 6–10), 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 field marigold
Field marigold sits happiest at around 40–65% relative humidity. Tolerates average outdoor humidity. Good air circulation reduces powdery mildew risk, which can affect plants in humid, sheltered spots. Avoid overhead watering and dense planting. 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.
Field marigold temperature & humidity — frequently asked questions
What temperature is best for field marigold?
Field marigold grows best between 7–20 °C optimal; tolerates light frost to −5 °C (45–68 °F optimal; tolerates light frost to 23 °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 field marigold tolerate?
Field marigold starts to suffer below roughly 7°C. It tolerates a cold dormant period within USDA 6–10 (cool-season annual; self-seeds in zones 6–10), but a wet cold root zone is more dangerous than cold air.
What humidity does field marigold need?
Field marigold prefers about 40–65% relative humidity. Tolerates average outdoor humidity. Good air circulation reduces powdery mildew risk, which can affect plants in humid, sheltered spots. Avoid overhead watering and dense planting.
How do I raise humidity for field marigold?
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 field marigold live outside?
Field marigold is rated for USDA zone 6–10 (cool-season annual; self-seeds in zones 6–10) 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 field marigold care
In the UK? Keeping field marigold warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full field marigold care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.