Plant care
Eaton's Firecrackertemperature & humidity
Penstemon eatonii
More about eaton's firecracker
Ideal temperature for eaton's firecracker
Temperature kills fewer eaton's firecracker 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 −20°C to 42°C (−4°F to 108°F) is fine; the spot you put the plant in matters more. Below roughly 20°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Eaton's Firecracker is comparatively hardy (USDA 4–9, RHS H6). 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 eaton's firecracker
Eaton's Firecracker sits happiest at around Very low (10–35% RH) relative humidity. Adapted to the arid conditions of the Colorado Plateau and Mojave Desert margins. Very low tolerance for high humidity. In the eastern US or Pacific Northwest, failure from crown and root rot in humid conditions is common — grow in containers with gritty mix if necessary. 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.
Eaton's Firecracker temperature & humidity — frequently asked questions
What temperature is best for eaton's firecracker?
Eaton's Firecracker grows best between −20°C to 42°C (−4°F to 108°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 eaton's firecracker tolerate?
Eaton's Firecracker starts to suffer below roughly 20°C. It tolerates a cold dormant period within USDA 4–9, but a wet cold root zone is more dangerous than cold air.
What humidity does eaton's firecracker need?
Eaton's Firecracker prefers about Very low (10–35% RH) relative humidity. Adapted to the arid conditions of the Colorado Plateau and Mojave Desert margins. Very low tolerance for high humidity. In the eastern US or Pacific Northwest, failure from crown and root rot in humid conditions is common — grow in containers with gritty mix if necessary.
How do I raise humidity for eaton's firecracker?
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 eaton's firecracker live outside?
Eaton's Firecracker is rated for USDA zone 4–9 and RHS hardiness H6. 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 eaton's firecracker care
In the UK? Keeping eaton's firecracker warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full eaton's firecracker care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.