When to plant Onion in Zone 5b
In Zone 5b, Onion: start seeds indoors around Feb 19–Mar 5; transplant outdoors around Apr 2–Apr 16. Expect to harvest around Jul 11–Jul 25.
| Step | When |
|---|---|
| Start seeds indoors | Feb 19 – Mar 5 |
| Transplant outdoors | Apr 2 – Apr 16 |
| Harvest | Jul 11 – Jul 25 |
Tip: Day-length sensitive — match the variety (long/short day) to your latitude for big bulbs.
Zone 5b averages a last spring frost around Apr 30 and a first fall frost around Oct 5. These are zone averages — look up your ZIP for your exact area.
See the full Zone 5b calendar in the tool →