Plant care
Geranium x oxonianum 'A.T. Johnson'temperature & humidity
Geranium x oxonianum 'A.T. Johnson'
More about geranium x oxonianum 'a.t. johnson'
Ideal temperature for geranium x oxonianum 'a.t. johnson'
Geranium x oxonianum 'A.T. Johnson' is comfortable in any room a person is comfortable in, roughly -20 to 27°C (-4 to 80°F). The mistakes are micro-climates: a north-facing window on a frosty night, a south-facing windowsill in a summer heatwave, the standing draught between an opened kitchen door and the radiator behind it. Read the room around the plant, not the thermostat. Below roughly -20°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Geranium x oxonianum 'A.T. Johnson' is comparatively hardy (USDA 4-8 (hardy garden perennial), RHS H7). 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 geranium x oxonianum 'a.t. johnson'
Geranium x oxonianum 'A.T. Johnson' sits happiest at around 40-70% relative humidity. A fully hardy outdoor perennial indifferent to humidity. Free-moving garden air keeps the foliage dry and limits rust and mildew; no humidity management is required. 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.
Geranium x oxonianum 'A.T. Johnson' temperature & humidity — frequently asked questions
What temperature is best for geranium x oxonianum 'a.t. johnson'?
Geranium x oxonianum 'A.T. Johnson' grows best between -20 to 27°C (-4 to 80°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 geranium x oxonianum 'a.t. johnson' tolerate?
Geranium x oxonianum 'A.T. Johnson' starts to suffer below roughly -20°C. It tolerates a cold dormant period within USDA 4-8 (hardy garden perennial), but a wet cold root zone is more dangerous than cold air.
What humidity does geranium x oxonianum 'a.t. johnson' need?
Geranium x oxonianum 'A.T. Johnson' prefers about 40-70% relative humidity. A fully hardy outdoor perennial indifferent to humidity. Free-moving garden air keeps the foliage dry and limits rust and mildew; no humidity management is required.
How do I raise humidity for geranium x oxonianum 'a.t. johnson'?
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 geranium x oxonianum 'a.t. johnson' live outside?
Geranium x oxonianum 'A.T. Johnson' is rated for USDA zone 4-8 (hardy garden perennial) and RHS hardiness H7. 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 geranium x oxonianum 'a.t. johnson' care
In the UK? Keeping geranium x oxonianum 'a.t. johnson' warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full geranium x oxonianum 'a.t. johnson' care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.