When to plant Onion in Zone 5a
In Zone 5a, Onion: start seeds indoors around Feb 24–Mar 10; transplant outdoors around Apr 7–Apr 21. Expect to harvest around Jul 16–Jul 30.
| Step | When |
|---|---|
| Start seeds indoors | Feb 24 – Mar 10 |
| Transplant outdoors | Apr 7 – Apr 21 |
| Harvest | Jul 16 – Jul 30 |
Tip: Day-length sensitive — match the variety (long/short day) to your latitude for big bulbs.
Zone 5a averages a last spring frost around May 5 and a first fall frost around Oct 1. These are zone averages — look up your ZIP for your exact area.
See the full Zone 5a calendar in the tool →