When to Plant Onions: Spring and Fall Planting by Zone
The best time to plant onion sets, transplants and seeds in each USDA zone, fall planting for overwintering onions, and timing in the Southern Hemisphere.
In cold and temperate regions, plant onions in early spring, as soon as the soil can be worked, usually 2–4 weeks before the last frost. In warm regions (zones 8–10), plant short-day onions in autumn or early winter for a spring harvest.
Planting Times by Zone
| USDA zone | Type | Plant | Harvest |
|---|---|---|---|
| 3–5 | Long-day | April – May | August – September |
| 6 | Long or intermediate | March – April | July – August |
| 7 | Intermediate or short-day | February – March, or fall for overwintering | June – July |
| 8–9 | Short-day | October – January | April – June |
| 10 | Short-day | October – December | March – May |
Starting Seeds
Sow indoors 8–10 weeks before transplanting. In warm zones, sow seed directly in early autumn.
Fall-Planted Onions
In zones 6–8 and in the UK, hardy overwintering varieties (e.g. 'Senshyu', 'Radar', 'Electric') can be planted as sets in September–October for an early summer harvest.
Southern Hemisphere
Plant short-day onions in autumn (March–May) and long-day types in late winter to spring (August–September).
More Onion Guides
- How to Grow Onions: The Complete Guide
- Short-day vs long-day onions
- Onion sets vs seeds and planting
- Why onions bolt
Frequently Asked Questions
Can I plant onions in the fall?
Yes, short-day and overwintering varieties in mild and temperate zones.
How late can you plant onions?
Long-day onions planted after late spring have too little time to grow leaves before bulbing and stay small.
TarlaTapan guides focus on practical, field-tested growing advice. Corrections and suggestions are welcome at info@tarlatapan.tr.