Plant care
Water Clover Ferntemperature & humidity
Marsilea mutica
More about water clover fern
Ideal temperature for water clover fern
Aim for 18-28°C (64-82°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 18°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Water Clover Fern is comparatively hardy (USDA 6-10 in ponds; overwinter the rhizome frost-free in colder zones, 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 water clover fern
Water Clover Fern sits happiest at around Ambient (aquatic) relative humidity. Humidity is irrelevant because the plant grows in or on water; the leaves draw moisture from the pond or bowl directly. In an open paludarium, surrounding air stays naturally humid above the water surface. 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.
Water Clover Fern temperature & humidity — frequently asked questions
What temperature is best for water clover fern?
Water Clover Fern grows best between 18-28°C (64-82°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 water clover fern tolerate?
Water Clover Fern starts to suffer below roughly 18°C. It tolerates a cold dormant period within USDA 6-10 in ponds; overwinter the rhizome frost-free in colder zones, but a wet cold root zone is more dangerous than cold air.
What humidity does water clover fern need?
Water Clover Fern prefers about Ambient (aquatic) relative humidity. Humidity is irrelevant because the plant grows in or on water; the leaves draw moisture from the pond or bowl directly. In an open paludarium, surrounding air stays naturally humid above the water surface.
How do I raise humidity for water clover fern?
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 water clover fern live outside?
Water Clover Fern is rated for USDA zone 6-10 in ponds; overwinter the rhizome frost-free in colder zones 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 water clover fern care
In the UK? Keeping water clover fern warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full water clover fern care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.