🧅 Onion
Leaves first, bulbs later — day length tells it when to finish.
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, 30) − 5), and Onion is ready when that total reaches 1050. That is why the same seed takes a very different number of days in Dublin and in Guangzhou.
| Base temperature | 5°CBelow this, the plant accumulates no growing degree days at all. |
|---|---|
| Degree days to maturity | 1050 °C·dThe heat budget it must accumulate before it is ready to pick. |
| Comfortable range | 8–28°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 | 31°CAbove this the plant slows down and stops setting fruit well. |
| Typical time to harvest | 90–110 days |
| Yield per bed | 10 onions |
Things worth knowing
- Onion varieties are classed by day length — a long-day onion near the equator grows leaves forever.
- Chopping onions releases a tear-inducing compound; chill them first and you'll cry much less.
Where and when to sow Onion
Pick your city to see the months when Onion scores well against that city's real climate records: