Plant care
Roundleaf Pickerelweedtemperature & humidity
Pontederia rotundifolia
More about roundleaf pickerelweed
Ideal temperature for roundleaf pickerelweed
Roundleaf Pickerelweed is comfortable in any room a person is comfortable in, roughly 15–35 °C (active growth); minimum 10 °C to avoid damage (59–95 °F (active growth); minimum 50 °F to avoid damage). 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 15°C the damage starts — soft blackened patches, translucent leaves, sometimes overnight.
Cold tolerance & winter care
Roundleaf Pickerelweed is frost-tender (USDA 9-11, RHS H2). It cannot survive a frost, so in most of the US and UK it lives indoors year-round or summers outside and comes back in well before the first autumn frost — once nights drop toward 10-12°C is the cue, not the first frost warning. Acclimate it over a week when moving between indoors and out so the leaves do not shock.
Humidity for roundleaf pickerelweed
Roundleaf Pickerelweed sits happiest at around High (naturally high in tropical origin habitats) relative humidity. Thrives in the naturally humid environment above a pond surface; no additional humidity management is needed in outdoor pond culture. 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.
Roundleaf Pickerelweed temperature & humidity — frequently asked questions
What temperature is best for roundleaf pickerelweed?
Roundleaf Pickerelweed grows best between 15–35 °C (active growth); minimum 10 °C to avoid damage (59–95 °F (active growth); minimum 50 °F to avoid damage). 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 roundleaf pickerelweed tolerate?
Roundleaf Pickerelweed starts to suffer below roughly 15°C. It is frost-tender and will be damaged or killed by a frost, so bring it indoors once nights fall toward 10-12°C.
What humidity does roundleaf pickerelweed need?
Roundleaf Pickerelweed prefers about High (naturally high in tropical origin habitats) relative humidity. Thrives in the naturally humid environment above a pond surface; no additional humidity management is needed in outdoor pond culture.
How do I raise humidity for roundleaf pickerelweed?
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 roundleaf pickerelweed live outside?
Roundleaf Pickerelweed is rated for USDA zone 9-11 and RHS hardiness H2. Outside that range it must come indoors before the first frost — treat any outdoor stint as a summer holiday, not a permanent home.
More roundleaf pickerelweed care
In the UK? Keeping roundleaf pickerelweed warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full roundleaf pickerelweed care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.