When to plant Cosmos in Zone 10a
In Zone 10a, Cosmos: direct sow outdoors around Jan 31–Feb 14. Expect to harvest around Apr 1–Apr 15.
| Step | When |
|---|---|
| Direct sow outdoors | Jan 31 – Feb 14 |
| Harvest | Apr 1 – Apr 15 |
Tip: Thrives on neglect — too-rich soil gives leaves at the expense of flowers.
Zone 10a averages a last spring frost around Jan 31 and a first fall frost around Dec 28. These are zone averages — look up your ZIP for your exact area.
See the full Zone 10a calendar in the tool →