When can I plant Cosmos in Zone 10a

The USDA Zone info is a great tool for gardeners to help us figure out our gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for our area.

The USDA zone info for Zone 10a should be reviewed to determine when it's a good idea to plant cosmos.


Planting Calendar for Cosmos

Frost tolerance for cosmos: Tolerant of a very small amount of frost.
When you should plant them: Up to 3 weeks before last frost.

Cosmos do ok in moderate cold which means that you can start planting them slightly earlier than other plants that might not handle the cold.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant cosmos
Possibly ok, but a risky time to plant cosmos
Probably not a good time to plant cosmos

The earliest that you can plant cosmos in Zone 10a is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant cosmos and expect a good harvest is probably September. If you wait any later than that and your cosmos may not have a chance to really do well. You can get started a couple of weeks earlier by starting your cosmos indoors.

Last Frost Date

In Zone 10a the average date of last frost happens on January 31. In the coldest months of winter we should expect an average low temperature of 30°F.

Always keep in mind that USDA zone info for Zone 10a is just an average and our actual date of last frost changes from year to year. Half of the time in Zone 10a we get a frost after January 31 so be sure to be ready to cover your cosmos in the event of one of those late frosts.

USDA Zone Info for Zone 10a

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)January 31
Average Date of First Frost (fall)December 15
Lowest Expected Low30°F
Highest Expected Low35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in Zone 10a

You may be interested in our other planting guides for Zone 10a.