Onions planting windows by zone
| Zone | Main planting window | |
|---|---|---|
| Zone 1 | May 4 – May 18 | transplant outdoors |
| Zone 2 | Apr 18 – May 2 | transplant outdoors |
| Zone 3 | Apr 3 – Apr 17 | transplant outdoors |
| Zone 4 | Mar 24 – Apr 7 | transplant outdoors |
| Zone 5 | Mar 11 – Mar 25 | transplant outdoors |
| Zone 6 | Feb 27 – Mar 13 | transplant outdoors |
| Zone 7 | Feb 16 – Mar 2 | transplant outdoors |
| Zone 8 | Feb 1 – Feb 15 | transplant outdoors |
| Zone 9 | Jan 9 – Jan 23 | transplant outdoors |
| Zone 10 | Dec 14 – Dec 28 | transplant outdoors |
| Zone 11 | Coolest months (Oct–Mar) | frost-free |
| Zone 12 | Coolest months (Oct–Mar) | frost-free |
| Zone 13 | Coolest months (Oct–Mar) | frost-free |
Each zone link above has the complete schedule — indoor seed-starting, direct sowing, and season-fit notes. Zone dates are typical medians; for windows built on your own city's frost dates, use the frost date lookup and planting calendar.