Plant care
Mustard Greens 'Red Giant'temperature & humidity
Brassica juncea var. rugosa 'Red Giant'
More about mustard greens 'red giant'
Ideal temperature for mustard greens 'red giant'
Temperature kills fewer mustard greens 'red giant' 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 10-24°C (50-75°F) is fine; the spot you put the plant in matters more. Below roughly 10°C growth pauses; cold beyond that pushes it into dormancy rather than killing it outright.
Cold tolerance & winter care
Mustard Greens 'Red Giant' is comparatively hardy (USDA Cool-season annual, zones 2-11; mature leaves tolerate frost to about -6°C, often sweetening after a light frost, RHS H5 (frost-hardy leaves; grown as an annual)). 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 mustard greens 'red giant'
Mustard Greens 'Red Giant' sits happiest at around 40-70% relative humidity. Outdoor leafy crop governed by soil moisture, not air humidity. Space plants for airflow to reduce white blister and downy mildew on the broad leaves. 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.
Mustard Greens 'Red Giant' temperature & humidity — frequently asked questions
What temperature is best for mustard greens 'red giant'?
Mustard Greens 'Red Giant' grows best between 10-24°C (50-75°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 mustard greens 'red giant' tolerate?
Mustard Greens 'Red Giant' starts to suffer below roughly 10°C. It tolerates a cold dormant period within USDA Cool-season annual, zones 2-11; mature leaves tolerate frost to about -6°C, often sweetening after a light frost, but a wet cold root zone is more dangerous than cold air.
What humidity does mustard greens 'red giant' need?
Mustard Greens 'Red Giant' prefers about 40-70% relative humidity. Outdoor leafy crop governed by soil moisture, not air humidity. Space plants for airflow to reduce white blister and downy mildew on the broad leaves.
How do I raise humidity for mustard greens 'red giant'?
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 mustard greens 'red giant' live outside?
Mustard Greens 'Red Giant' is rated for USDA zone Cool-season annual, zones 2-11; mature leaves tolerate frost to about -6°C, often sweetening after a light frost and RHS hardiness H5 (frost-hardy leaves; grown as an annual). 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 mustard greens 'red giant' care
In the UK? Keeping mustard greens 'red giant' warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full mustard greens 'red giant' care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.