When to plant Cosmos in Zone 8b
In Zone 8b, Cosmos: direct sow outdoors around Mar 15–Mar 29. Expect to harvest around May 14–May 28.
| Step | When |
|---|---|
| Direct sow outdoors | Mar 15 – Mar 29 |
| Harvest | May 14 – May 28 |
Tip: Thrives on neglect — too-rich soil gives leaves at the expense of flowers.
Zone 8b averages a last spring frost around Mar 15 and a first fall frost around Nov 25. These are zone averages — look up your ZIP for your exact area.
See the full Zone 8b calendar in the tool →