Plant care
Fordhook Lima Beantemperature & humidity
Phaseolus lunatus 'Fordhook'
More about fordhook lima bean
Ideal temperature for fordhook lima bean
Temperature kills fewer fordhook lima bean 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 21–35 °C (70–95 °F) is fine; the spot you put the plant in matters more. Below roughly 21°C the damage starts — soft blackened patches, translucent leaves, sometimes overnight.
Cold tolerance & winter care
Fordhook Lima Bean is frost-tender (USDA 3–11 (frost-tender annual in most zones; perennial vine in zones 10–12), RHS H1b). It cannot survive a frost, so in most of the US and UK it lives indoors year-round or summers outside and comes back in well before the first autumn frost — once nights drop toward 10-12°C is the cue, not the first frost warning. Acclimate it over a week when moving between indoors and out so the leaves do not shock.
Humidity for fordhook lima bean
Fordhook Lima Bean sits happiest at around 40–70% relative humidity. Adapts to a range of humidity levels. Very high humidity (above 80%) combined with warmth promotes downy mildew and botrytis pod rot. Space plants at least 15–20 cm apart in rows for air circulation. 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.
Fordhook Lima Bean temperature & humidity — frequently asked questions
What temperature is best for fordhook lima bean?
Fordhook Lima Bean grows best between 21–35 °C (70–95 °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 fordhook lima bean tolerate?
Fordhook Lima Bean starts to suffer below roughly 21°C. It is frost-tender and will be damaged or killed by a frost, so bring it indoors once nights fall toward 10-12°C.
What humidity does fordhook lima bean need?
Fordhook Lima Bean prefers about 40–70% relative humidity. Adapts to a range of humidity levels. Very high humidity (above 80%) combined with warmth promotes downy mildew and botrytis pod rot. Space plants at least 15–20 cm apart in rows for air circulation.
How do I raise humidity for fordhook lima bean?
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 fordhook lima bean live outside?
Fordhook Lima Bean is rated for USDA zone 3–11 (frost-tender annual in most zones; perennial vine in zones 10–12) and RHS hardiness H1b. Outside that range it must come indoors before the first frost — treat any outdoor stint as a summer holiday, not a permanent home.
More fordhook lima bean care
In the UK? Keeping fordhook lima bean warm in a UK home covers the radiator, single-glazing and heating-season humidity angle. Temperature and humidity are one piece. See the full fordhook lima bean care guide, its cold-hardiness guide, and watering schedule — humidity and watering problems are easy to confuse.