When to plant bulb onion
Vegetable, hardy
Sow or set out 2–4 weeks before the last frost. Bulbs take about 100–120 days. CSU's germination minimum is 35°F, while Wisconsin says wait to plant onion seed until the soil is 60°F.
The general rule
- Sow outdoors
- 2–4 weeks before the last spring frost
- Plant when soil reaches
- 60°F
- Days to maturity
- 100–120 days
What that means in different climates
The same rule applied to the safer frost dates of cities from cold to frost-free.
| City | Last frost · safer | Sow outdoors |
|---|---|---|
| San Jose, CA | Jan 23 | Dec 26 – Jan 9 |
| Tucson, AZ | Mar 2 | Feb 2 – Feb 16 |
| Portland, OR | Mar 21 | Feb 21 – Mar 7 |
| Baltimore, MD | Apr 4 | Mar 7 – Mar 21 |
| New York, NY | Apr 12 | Mar 15 – Mar 29 |
| Nashville, TN | Apr 16 | Mar 19 – Apr 2 |
| Louisville, KY | Apr 23 | Mar 26 – Apr 9 |
| Omaha, NE | May 6 | Apr 8 – Apr 22 |
| Colorado Springs, CO | May 15 | Apr 17 – May 1 |
| Miami, FL | Frost rare | Frost is rare: fall and winter (soil 60°F+). |