When to plant Sunflower in Zone 1b
In Zone 1b, Sunflower: direct sow outdoors around Jun 10–Jul 1. Expect to harvest around Aug 19–Sep 9.
| Step | When |
|---|---|
| Direct sow outdoors | Jun 10 – Jul 1 |
| Harvest | Aug 19 – Sep 9 |
Tip: Direct-sow once frost has passed; sow every two weeks for a long succession of blooms.
Zone 1b averages a last spring frost around Jun 10 and a first fall frost around Aug 20. These are zone averages — look up your ZIP for your exact area.
See the full Zone 1b calendar in the tool →