When to plant Cosmos in Zone 9b
In Zone 9b, Cosmos: direct sow outdoors around Feb 15–Mar 1. Expect to harvest around Apr 16–Apr 30.
| Step | When |
|---|---|
| Direct sow outdoors | Feb 15 – Mar 1 |
| Harvest | Apr 16 – Apr 30 |
Tip: Thrives on neglect — too-rich soil gives leaves at the expense of flowers.
Zone 9b averages a last spring frost around Feb 15 and a first fall frost around Dec 15. These are zone averages — look up your ZIP for your exact area.
See the full Zone 9b calendar in the tool →