When to plant Cosmos in Zone 6a
In Zone 6a, Cosmos: direct sow outdoors around Apr 21–May 5. Expect to harvest around Jun 20–Jul 4.
| Step | When |
|---|---|
| Direct sow outdoors | Apr 21 – May 5 |
| Harvest | Jun 20 – Jul 4 |
Tip: Thrives on neglect — too-rich soil gives leaves at the expense of flowers.
Zone 6a averages a last spring frost around Apr 21 and a first fall frost around Oct 17. These are zone averages — look up your ZIP for your exact area.
See the full Zone 6a calendar in the tool →