When to plant Cosmos in Zone 5b
In Zone 5b, Cosmos: direct sow outdoors around Apr 30–May 14. Expect to harvest around Jun 29–Jul 13.
| Step | When |
|---|---|
| Direct sow outdoors | Apr 30 – May 14 |
| Harvest | Jun 29 – Jul 13 |
Tip: Thrives on neglect — too-rich soil gives leaves at the expense of flowers.
Zone 5b averages a last spring frost around Apr 30 and a first fall frost around Oct 5. These are zone averages — look up your ZIP for your exact area.
See the full Zone 5b calendar in the tool →