🧅 When to Plant Onions
Start very early indoors or use sets
📅 Planting Calendar by USDA Zone
Onions is a cool-season crop — plant it around your last spring frost, and you can often start it earlier indoors or sow again for a fall harvest. Find the exact start-indoors, transplant, and direct-sow dates for your USDA zone in the table below.
Select your zone to highlight your dates. All dates are calculated from each zone's average frost dates — see how we calculate them.
| Zone | Last Frost | Start Indoors | Transplant | Direct Sow |
|---|---|---|---|---|
| Zone 2A | May 30 | Mar 7 | May 2 | Apr 18 |
| Zone 3B | May 15 | Feb 20 | Apr 17 | Apr 3 |
| Zone 4A | May 8 | Feb 13 | Apr 10 | Mar 27 |
| Zone 4B | May 1 | Feb 6 | Apr 3 | Mar 20 |
| Zone 5A | Apr 25 | Jan 31 | Mar 28 | Mar 14 |
| Zone 5B | Apr 18 | Jan 24 | Mar 21 | Mar 7 |
| Zone 6A | Apr 21 | Jan 27 | Mar 24 | Mar 10 |
| Zone 6B | Apr 10 | Jan 16 | Mar 13 | Feb 27 |
| Zone 7A | Apr 5 | Jan 11 | Mar 8 | Feb 22 |
| Zone 7B | Mar 28 | Jan 3 | Feb 28 | Feb 14 |
| Zone 8A | Mar 20 | Dec 26 | Feb 20 | Feb 6 |
| Zone 8B | Mar 12 | Dec 18 | Feb 12 | Jan 29 |
| Zone 9A | Feb 28 | Dec 6 | Jan 31 | Jan 17 |
| Zone 9B | Feb 15 | Nov 23 | Jan 18 | Jan 4 |
| Zone 10A | Feb 1 | Nov 9 | Jan 4 | Dec 21 |
| Zone 10B | Jan 15 | Oct 23 | Dec 18 | Dec 4 |
| Zone 11A | Jan 1 | Oct 9 | Dec 4 | Nov 20 |
Onions are a garden staple. Choose the right day-length variety for your latitude for best results.
Top Growing Tips
- Short-day varieties for zones 7+ (south), long-day for zones 6 and north
- Start from sets (small bulbs) for easiest results
- Stop watering when tops start to fall over
- Cure in a warm, dry spot for 2-3 weeks before storing
- Day-neutral varieties work in any zone
Companion Planting
Good companions: beets, carrots, lettuce, tomatoes, chamomile
Avoid planting near: beans, peas
Harvest Timeline
90-120 days from sets, 100-175 days from seed
Growing onions in your region?
These dates come from your zone's frost windows. For the full month-by-month plan — succession sowing, variety picks, and timing tuned to your climate, not just your zone — our regional vegetable-gardening guides cover your area start to finish.
Find your regional growing guide