When to plant sunflower
Flower, tender
Penn State lists sunflower with tender annuals: start seed about 4–6 weeks before the last frost and do not plant outdoors until frost danger has passed. No crop-specific days-to-bloom or soil temperature was on that page.
The general rule
- Start indoors
- 4–6 weeks before the last spring frost
- Days to maturity
- Varies by variety
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 | Start indoors |
|---|---|---|
| San Jose, CA | Jan 23 | Dec 12 – Dec 26 |
| Tucson, AZ | Mar 2 | Jan 19 – Feb 2 |
| Portland, OR | Mar 21 | Feb 7 – Feb 21 |
| Baltimore, MD | Apr 4 | Feb 21 – Mar 7 |
| New York, NY | Apr 12 | Mar 1 – Mar 15 |
| Nashville, TN | Apr 16 | Mar 5 – Mar 19 |
| Louisville, KY | Apr 23 | Mar 12 – Mar 26 |
| Omaha, NE | May 6 | Mar 25 – Apr 8 |
| Colorado Springs, CO | May 15 | Apr 3 – Apr 17 |
| Miami, FL | Frost rare | Frost is rare: late winter to spring; late summer to fall. |