Plant care
Hemianthus micranthemoidestemperature & humidity
Hemianthus micranthemoides
More about hemianthus micranthemoides
Ideal temperature for hemianthus micranthemoides
Aim for 20-28°C (68-82°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 20°C the damage starts — soft blackened patches, translucent leaves, sometimes overnight.
Cold tolerance & winter care
Hemianthus micranthemoides is frost-tender (USDA Not applicable (tropical aquarium plant, indoor), RHS H1b). 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 hemianthus micranthemoides
Hemianthus micranthemoides sits happiest at around 100% (submerged) relative humidity. An aquatic stem plant grown fully underwater, so atmospheric humidity does not apply. It can be cultivated emersed in saturated, near-100%-humidity conditions before flooding. 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.
Hemianthus micranthemoides temperature & humidity — frequently asked questions
What temperature is best for hemianthus micranthemoides?
Hemianthus micranthemoides grows best between 20-28°C (68-82°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 hemianthus micranthemoides tolerate?
Hemianthus micranthemoides starts to suffer below roughly 20°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 hemianthus micranthemoides need?
Hemianthus micranthemoides prefers about 100% (submerged) relative humidity. An aquatic stem plant grown fully underwater, so atmospheric humidity does not apply. It can be cultivated emersed in saturated, near-100%-humidity conditions before flooding.
How do I raise humidity for hemianthus micranthemoides?
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 hemianthus micranthemoides live outside?
Hemianthus micranthemoides is rated for USDA zone Not applicable (tropical aquarium plant, indoor) and RHS hardiness H1b. Outside that range it must come indoors before the first frost — treat any outdoor stint as a summer holiday, not a permanent home.
More hemianthus micranthemoides care
In the UK? Keeping hemianthus micranthemoides warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full hemianthus micranthemoides care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.