When can I plant Cosmos in Zone 9a

Before planting it is a good idea to find our USDA Zone info to estimate our garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for our area.

In Zone 9a you can estimate when it's possible to plant cosmos by reviewing the USDA zone info.


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.

You can plant cosmos just a tiny bit earlier in the year because they do ok in moderate 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 9a 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. Any later than that and your cosmos may not have a chance to grow to maturity. If you are starting your cosmos indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is February 15 in Zone 9a. In the coldest months of winter we can expect an average low temperature of 20°F.

Just be sure to remember that our actual date of last frost is not always accurate because it is based on the USDA zone info for Zone 9a and it will vary from year to year. Half of the time in Zone 9a last frost occurs after February 15 so always be ready to protect your cosmos if we have one of those late frosts.

USDA Zone Info for Zone 9a

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)February 15
Average Date of First Frost (fall)December 15
Lowest Expected Low20°F
Highest Expected Low25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Zone 9a

You may be interested in our other planting guides for Zone 9a.