🫘 Broad bean
The hardiest bean there is. Sow in autumn, overwinter it, and crop a month before a spring sowing.
Broad bean at a glance
Is Broad bean frost tolerant?
Yes — it is one of the hardier crops. It shrugs off frost down to -6°C and is only killed below -12°C.
What temperature does Broad bean grow best in?
It grows best between 6 and 22°C. Below 3°C it stops growing altogether, and above 26°C it slows down.
How many days does Broad bean take to mature?
About 90–120 days. That is a typical figure: it needs roughly 950 °C·d of warmth above 3°C, so a warm season gets it there sooner and a cool one later. The city calendars below give the sow and harvest dates for each place.
Is Broad bean a cool-season or warm-season crop?
A cool-season crop. It does best in the mild weather of spring and autumn (and through winter where winters are mild), and slows down in summer heat above 26°C.
What the numbers mean
These are the actual parameters this game runs on. Growth is driven by growing degree days: each day contributes max(0, min(mean temp, 26) − 3), and Broad bean is ready when that total reaches 950. That is why the same seed takes a very different number of days in Dublin and in Guangzhou.
| Base temperature | 3°CBelow this, the plant accumulates no growing degree days at all. |
|---|---|
| Degree days to maturity | 950 °C·dThe heat budget it must accumulate before it is ready to pick. |
| Comfortable range | 6–22°CWhere it grows without stress. |
| Frost damage below | -6°CLeaves start taking frost damage below this low. |
| Killed below | -12°CBelow this it does not come back. |
| Heat stress above | 26°CAbove this the plant slows down and stops setting fruit well. |
| Typical time to harvest | 90–120 days |
| Yield per bed | 12 pods |
Things worth knowing
- Broad beans survive to around -6°C, one of the very few beans that can stay out all winter.
- Their root nodules fix nitrogen — dig the plants in after cropping and the next leaf crop notices.
Where and when to sow Broad bean
Pick your city to see the months when Broad bean scores well against that city's real climate records: