Plant care
Trailing globe amaranthtemperature & humidity
Gomphrena serrata
More about trailing globe amaranth
Ideal temperature for trailing globe amaranth
Temperature kills fewer trailing globe amaranth plants than you'd think. What kills them is the micro-climate within a normal-temperature room — a leaf pressed against single-glazed winter glass, the hot dry updraft directly above a radiator, the cold blast from an AC vent. The thermostat reading at 18–38°C (64–100°F) is fine; the spot you put the plant in matters more. Below roughly 18°C the damage starts — soft blackened patches, translucent leaves, sometimes overnight.
Cold tolerance & winter care
Trailing globe amaranth is frost-tender (USDA 2–11 (grown as annual), 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 trailing globe amaranth
Trailing globe amaranth sits happiest at around 30–70% relative humidity. Very tolerant of heat and humidity. Performs well in hot, sunny climates and is more resilient in humid summer conditions than many other annuals. Excellent for hot, exposed sites where other trailing plants might struggle. 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.
Trailing globe amaranth temperature & humidity — frequently asked questions
What temperature is best for trailing globe amaranth?
Trailing globe amaranth grows best between 18–38°C (64–100°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 trailing globe amaranth tolerate?
Trailing globe amaranth starts to suffer below roughly 18°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 trailing globe amaranth need?
Trailing globe amaranth prefers about 30–70% relative humidity. Very tolerant of heat and humidity. Performs well in hot, sunny climates and is more resilient in humid summer conditions than many other annuals. Excellent for hot, exposed sites where other trailing plants might struggle.
How do I raise humidity for trailing globe 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 trailing globe amaranth live outside?
Trailing globe amaranth is rated for USDA zone 2–11 (grown as annual) 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 trailing globe amaranth care
In the UK? Keeping trailing globe 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 trailing globe amaranth care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.