Plant care
Double Marsh Marigoldtemperature & humidity
Caltha palustris 'Flore Pleno'
More about double marsh marigold
Ideal temperature for double marsh marigold
Temperature kills fewer double marsh marigold 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 -30 to 25°C (-22 to 77°F) is fine; the spot you put the plant in matters more. Below roughly -30°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Double Marsh Marigold is comparatively hardy (USDA 3-7, RHS H7). 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 double marsh marigold
Double Marsh Marigold sits happiest at around High (bog/pond margin; naturally humid microclimate) relative humidity. Naturally grows in humid, waterside habitats. Ambient humidity at the pond margin is sufficient; no supplemental misting is required. In very dry summers, mulch around the base if growing in a bog bed to retain moisture and maintain a cool root run. 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.
Double Marsh Marigold temperature & humidity — frequently asked questions
What temperature is best for double marsh marigold?
Double Marsh Marigold grows best between -30 to 25°C (-22 to 77°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 double marsh marigold tolerate?
Double Marsh Marigold starts to suffer below roughly -30°C. It tolerates a cold dormant period within USDA 3-7, but a wet cold root zone is more dangerous than cold air.
What humidity does double marsh marigold need?
Double Marsh Marigold prefers about High (bog/pond margin; naturally humid microclimate) relative humidity. Naturally grows in humid, waterside habitats. Ambient humidity at the pond margin is sufficient; no supplemental misting is required. In very dry summers, mulch around the base if growing in a bog bed to retain moisture and maintain a cool root run.
How do I raise humidity for double marsh 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 double marsh marigold live outside?
Double Marsh Marigold is rated for USDA zone 3-7 and RHS hardiness H7. 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 double marsh marigold care
In the UK? Keeping double marsh 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 double marsh marigold care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.