Plant care
Green Milkweedtemperature & humidity
Asclepias viridis
More about green milkweed
Ideal temperature for green milkweed
Temperature kills fewer green milkweed 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 -15 to 38°C (5 to 100°F) is fine; the spot you put the plant in matters more. Below roughly -15°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Green Milkweed is comparatively hardy (USDA 5-9, RHS H5). 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 green milkweed
Green Milkweed sits happiest at around Low to moderate; 30–65% RH relative humidity. Adapted to the humid subtropical and continental climates of the south-central US. More tolerant of humidity than western xeric milkweeds. Good air circulation reduces fungal disease incidence. Not suited to perpetually wet tropical 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.
Green Milkweed temperature & humidity — frequently asked questions
What temperature is best for green milkweed?
Green Milkweed grows best between -15 to 38°C (5 to 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 green milkweed tolerate?
Green Milkweed starts to suffer below roughly -15°C. It tolerates a cold dormant period within USDA 5-9, but a wet cold root zone is more dangerous than cold air.
What humidity does green milkweed need?
Green Milkweed prefers about Low to moderate; 30–65% RH relative humidity. Adapted to the humid subtropical and continental climates of the south-central US. More tolerant of humidity than western xeric milkweeds. Good air circulation reduces fungal disease incidence. Not suited to perpetually wet tropical conditions.
How do I raise humidity for green milkweed?
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 green milkweed live outside?
Green Milkweed is rated for USDA zone 5-9 and RHS hardiness H5. 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 green milkweed care
In the UK? Keeping green milkweed warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full green milkweed care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.