Plant care
Pygmy Torch Amaranthtemperature & humidity
Amaranthus hypochondriacus
More about pygmy torch amaranth
Ideal temperature for pygmy torch amaranth
Aim for 20-38°C (68-100°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
Pygmy Torch Amaranth is frost-tender (USDA 2-11 (grown as warm-season annual), RHS H1c). 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 pygmy torch amaranth
Pygmy Torch Amaranth sits happiest at around 40-65% relative humidity. Tolerates moderate humidity well; a warm-season crop native to semi-arid regions of the Americas. Good air circulation at soil level reduces the risk of fungal stem and root diseases. 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.
Pygmy Torch Amaranth temperature & humidity — frequently asked questions
What temperature is best for pygmy torch amaranth?
Pygmy Torch Amaranth grows best between 20-38°C (68-100°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 pygmy torch amaranth tolerate?
Pygmy Torch Amaranth 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 pygmy torch amaranth need?
Pygmy Torch Amaranth prefers about 40-65% relative humidity. Tolerates moderate humidity well; a warm-season crop native to semi-arid regions of the Americas. Good air circulation at soil level reduces the risk of fungal stem and root diseases.
How do I raise humidity for pygmy torch amaranth?
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 pygmy torch amaranth live outside?
Pygmy Torch Amaranth is rated for USDA zone 2-11 (grown as warm-season annual) and RHS hardiness H1c. Outside that range it must come indoors before the first frost — treat any outdoor stint as a summer holiday, not a permanent home.
More pygmy torch amaranth care
In the UK? Keeping pygmy torch amaranth warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full pygmy torch amaranth care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.