Onion
Onion is a warm-temperate herbaceous crop that grows best in the 12–25°C range with 350–600 mm of rain, cropping over a 85–175-day season. Today it is grown mostly in India, China and United States.
How it grows
Onion is a bulb that grows just beneath the soil surface, under its green tops.
What it’s worth to grow
Farm-gate value = the price farmers are paid per kilogram (FAOSTAT producer prices, median of 577 positive country-year observations spanning 2018–2024). It tracks how costly and labour-intensive a crop is to grow — almonds and vanilla command a premium; potatoes and cereals are cheap staples.
Where Earth's climate suits onion
Climatic suitability only — scored for every 0.5° of the planet from this crop's temperature and rainfall tolerances (FAO EcoCrop) on AgroClim 1991–2025 normals (AgERA5 temperature, CHIRPS/ERA5 rainfall). It shows where the rain-fed climate permits the crop, not where it is grown today; irrigation lets many crops thrive in drier country than the map suggests (California, Egypt, the Indus and Nile).
Who grows it — and where the climate merely allows it
The climate where it grows
— mean monthly temperature ▍ monthly rainfall — averaged over the actual growing areas (the suitable cells) inside each country, so it reflects where the crop is really grown, not the national average. AgroClim 1991–2025 normals. The 🌧 badge is the last 3 months’ rainfall as a percentage of the 1991–2020 CHIRPS normal (through 2025-12) — the current drought/deluge signal.
Climate envelope · FAO EcoCrop
Deep bar = optimal range; pale bar = absolute tolerance. Beyond the pale bar the crop fails. Latitude tolerance ±60° · soil pH 4.3–8.3.
Growing calendar & hazards
An annual cycle of roughly 85–175 days from sowing to harvest, so it is timed to fall within the frost-free, adequately-wet part of the year for the location.
- Drought. Relatively drought-hardy, but a failed rainy season still cuts yield sharply where irrigation is absent.
- Heat. A cool-season crop that bolts or fails in summer heat; best grown in the shoulder seasons or at altitude.