When to plant Cosmos in Zone 11a
In Zone 11a, Cosmos: direct sow outdoors around Jan 1–Jan 15. Expect to harvest around Mar 2–Mar 16.
| Step | When |
|---|---|
| Direct sow outdoors | Jan 1 – Jan 15 |
| Harvest | Mar 2 – Mar 16 |
Tip: Thrives on neglect — too-rich soil gives leaves at the expense of flowers.
Zone 11a averages a last spring frost around Jan 1 and a first fall frost around Dec 31. These are zone averages — look up your ZIP for your exact area.
See the full Zone 11a calendar in the tool →