When to plant Onion seed
The planting dates depend on your average frost dates. Enter a ZIP code to get yours, or read the USDA table below.
| Average last freeze | Plant |
|---|---|
| Jan 30 | Jan 1 – 15 |
| Feb 8 | Jan 1 – 15 |
| Feb 18 | Jan 1 – 15 |
| Feb 28 | Jan 1 – Feb 15 |
| Mar 10 | Feb 1 – Mar 1 |
| Mar 20 | Feb 10 – Mar 10 |
| Mar 30 | Feb 20 – Mar 15 |
| Apr 10 | Mar 1 – Apr 1 |
| Apr 20 | Mar 15 – Apr 1 |
| Apr 30 | Mar 15 – Apr 15 |
| May 10 | Apr 1 – May 1 |
| May 20 | Apr 20 – May 15 |
| May 30 | May 1 – 30 |
| June 10 | May 10 – June 10 |
| Average first freeze | Plant by |
|---|---|
| Aug 30 | May 1 – June 1 |
| Sept 10 | May 1 – June 10 |
| Sept 20 | Generally spring-planted |
| Sept 30 | Generally spring-planted |
| Oct 10 | Generally spring-planted |
| Oct 20 | Generally spring-planted |
| Oct 30 | Not listed |
| Nov 10 | Not listed |
| Nov 20 | Sept 1 – Nov 1 |
| Nov 30 | Sept 1 – Nov 1 |
| Dec 10 | Sept 1 – Nov 1 |
| Dec 20 | Sept 15 – Nov 1 |
Source: USDA Home and Garden Bulletin No. 9 (1967), “Suburban and Farm Vegetable Gardens,” tables 4 and 5. The bulletin scan.