When to plant Sunflower in Zone 3a
In Zone 3a, Sunflower: direct sow outdoors around May 25–Jun 15. Expect to harvest around Aug 3–Aug 24.
| Step | When |
|---|---|
| Direct sow outdoors | May 25 – Jun 15 |
| Harvest | Aug 3 – Aug 24 |
Tip: Direct-sow once frost has passed; sow every two weeks for a long succession of blooms.
Zone 3a averages a last spring frost around May 25 and a first fall frost around Sep 8. These are zone averages — look up your ZIP for your exact area.
See the full Zone 3a calendar in the tool →