Plant care
Smokebush 'Royal Purple'temperature & humidity
Cotinus coggygria 'Royal Purple'
More about smokebush 'royal purple'
Ideal temperature for smokebush 'royal purple'
Smokebush 'Royal Purple' is comfortable in any room a person is comfortable in, roughly -20 to 30°C (-4 to 86°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
Smokebush 'Royal Purple' is comparatively hardy (USDA 5-8, 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 smokebush 'royal purple'
Smokebush 'Royal Purple' sits happiest at around Outdoor ambient relative humidity. A hardy garden shrub with no humidity requirements; ordinary outdoor air suits it. Good airflow helps prevent powdery mildew and verticillium in damp 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.
Smokebush 'Royal Purple' temperature & humidity — frequently asked questions
What temperature is best for smokebush 'royal purple'?
Smokebush 'Royal Purple' grows best between -20 to 30°C (-4 to 86°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 smokebush 'royal purple' tolerate?
Smokebush 'Royal Purple' starts to suffer below roughly -20°C. It tolerates a cold dormant period within USDA 5-8, but a wet cold root zone is more dangerous than cold air.
What humidity does smokebush 'royal purple' need?
Smokebush 'Royal Purple' prefers about Outdoor ambient relative humidity. A hardy garden shrub with no humidity requirements; ordinary outdoor air suits it. Good airflow helps prevent powdery mildew and verticillium in damp conditions.
How do I raise humidity for smokebush 'royal purple'?
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 smokebush 'royal purple' live outside?
Smokebush 'Royal Purple' is rated for USDA zone 5-8 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 smokebush 'royal purple' care
In the UK? Keeping smokebush 'royal purple' warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full smokebush 'royal purple' care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.