Plant care
Tunbridge Filmy Ferntemperature & humidity
Hymenophyllum tunbrigense
More about tunbridge filmy fern
Ideal temperature for tunbridge filmy fern
Tunbridge Filmy Fern is comfortable in any room a person is comfortable in, roughly 5–15°C (41–59°F). The mistakes are micro-climates: a north-facing window on a frosty night, a south-facing windowsill in a summer heatwave, the standing draught between an opened kitchen door and the radiator behind it. Read the room around the plant, not the thermostat. Below roughly 5°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Tunbridge Filmy Fern is comparatively hardy (USDA 7-9, RHS H6). 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 tunbridge filmy fern
Tunbridge Filmy Fern sits happiest at around 90–100% relative humidity. The highest humidity of any commonly grown fern. A sealed glass terrarium or Wardian case is the only practical way to maintain these levels indoors. Even a brief drop below 80% causes the translucent fronds to crisp and collapse; they may recover if rehydrated immediately, but repeated drying is fatal. 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.
Tunbridge Filmy Fern temperature & humidity — frequently asked questions
What temperature is best for tunbridge filmy fern?
Tunbridge Filmy Fern grows best between 5–15°C (41–59°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 tunbridge filmy fern tolerate?
Tunbridge Filmy Fern starts to suffer below roughly 5°C. It tolerates a cold dormant period within USDA 7-9, but a wet cold root zone is more dangerous than cold air.
What humidity does tunbridge filmy fern need?
Tunbridge Filmy Fern prefers about 90–100% relative humidity. The highest humidity of any commonly grown fern. A sealed glass terrarium or Wardian case is the only practical way to maintain these levels indoors. Even a brief drop below 80% causes the translucent fronds to crisp and collapse; they may recover if rehydrated immediately, but repeated drying is fatal.
How do I raise humidity for tunbridge filmy 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 tunbridge filmy fern live outside?
Tunbridge Filmy Fern is rated for USDA zone 7-9 and RHS hardiness H6. 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 tunbridge filmy fern care
In the UK? Keeping tunbridge filmy 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 tunbridge filmy fern care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.