Plant care
Gay's Pondweedtemperature & humidity
Potamogeton gayi
More about gay's pondweed
Ideal temperature for gay's pondweed
Aim for 15–28°C (59–82°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 15°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Gay's Pondweed is comparatively hardy (USDA 8–11 (South American origin but moderately cold-tolerant; suitable for outdoor ponds in mild temperate regions if given shelter from hard frosts), RHS H3). 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 gay's pondweed
Gay's Pondweed sits happiest at around Aquatic — not suited to emersed indoor cultivation relative humidity. A submerged aquatic plant adapted to life fully underwater. The thin linear leaves do not adapt to emersed growth in typical indoor humidity. Keep fully submerged in aquarium or pond conditions. 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.
Gay's Pondweed temperature & humidity — frequently asked questions
What temperature is best for gay's pondweed?
Gay's Pondweed grows best between 15–28°C (59–82°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 gay's pondweed tolerate?
Gay's Pondweed starts to suffer below roughly 15°C. It tolerates a cold dormant period within USDA 8–11 (South American origin but moderately cold-tolerant; suitable for outdoor ponds in mild temperate regions if given shelter from hard frosts), but a wet cold root zone is more dangerous than cold air.
What humidity does gay's pondweed need?
Gay's Pondweed prefers about Aquatic — not suited to emersed indoor cultivation relative humidity. A submerged aquatic plant adapted to life fully underwater. The thin linear leaves do not adapt to emersed growth in typical indoor humidity. Keep fully submerged in aquarium or pond conditions.
How do I raise humidity for gay's pondweed?
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 gay's pondweed live outside?
Gay's Pondweed is rated for USDA zone 8–11 (South American origin but moderately cold-tolerant; suitable for outdoor ponds in mild temperate regions if given shelter from hard frosts) and RHS hardiness H3. 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 gay's pondweed care
In the UK? Keeping gay's pondweed warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full gay's pondweed care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.