When to plant Cosmos in Zone 9a
In Zone 9a, Cosmos: direct sow outdoors around Feb 28–Mar 14. Expect to harvest around Apr 29–May 13.
| Step | When |
|---|---|
| Direct sow outdoors | Feb 28 – Mar 14 |
| Harvest | Apr 29 – May 13 |
Tip: Thrives on neglect — too-rich soil gives leaves at the expense of flowers.
Zone 9a averages a last spring frost around Feb 28 and a first fall frost around Dec 5. These are zone averages — look up your ZIP for your exact area.
See the full Zone 9a calendar in the tool →