Onion
Allium cepa
Cool‑season · frost‑tolerant · direct sow
90–120 days from seed to harvest
Onion is a cool-season bulb or stem vegetable in the amaryllis family that tolerates light frost. The usual start is direct sowing, and harvest is about 90–120 days from sowing (about 13 to 17 weeks).
Primary method: direct sow
Onion is usually sown outdoors. Calendar dates for your garden are on the when-to-plant page after you choose a place.
- Sow outside. Sow seed outdoors. Germination typically takes 7–12 days.
- Grow to harvest. The harvest clock starts when you sow seed. 90–120 days from sowing (about 13 to 17 weeks).
Time to harvest
Ready to harvest about 13 to 17 weeks after sowing.
- Sow
- Sprouting
- Growing
- Harvest, earliest to latest
Dates for your area: When to plant onion This guide has no calendar dates; they depend on your place.
Other start methods
Starting indoors is not the usual method for this plant.
Care basics
Sun: full sun, at least 6 hours of direct sun.
This plant tolerates light frost.
Types and varieties
Other names: Bulb onion, Common onion, Yellow onion, Red onion, White onion. Variety groups are not listed here.
Growing facts
| Attribute | Value |
|---|---|
| Plant name | Onion |
| Scientific name | Allium cepa |
| Family | Amaryllidaceae (amaryllis family) |
| Time to harvest | 90–120 days from sowing (about 13 to 17 weeks) |
| Days to germinate | 7–12 days |
| Ideal growing temperature | 15 – 24 °C |
| Minimum tolerable temperature | 4 °C |
| Maximum tolerable temperature | 30 °C |
| Start indoors | Not the usual method |
| Direct sow | Yes, usual method |
| Season type | Cool-season, tolerates light frost |
| Typical start method | Direct sow |
| Light | full sun, 6+ hours direct sun |
Glossary
- Ideal temperature
- The preferred daytime range for good growth.
- Tolerable temperature
- A wider range where the plant can still grow, less optimally.
- Harden off
- Gradually acclimating indoor seedlings to outdoor conditions before transplanting.
- Transplant
- Moving seedlings into the garden.
- Days to harvest
- The usual time to harvest, counted from the start point named beside the number (seed, transplant, or planting).