When can I plant Cosmos in Zone 8a

The USDA Zone info is a great tool for gardeners to help us determine our gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for our area.

A common way of determining when you can plant cosmos is to look at the USDA zone info for Zone 8a.


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 very little cold which means that you can plant them just a tiny bit earlier in the year than other frost tender plants.

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 8a is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant cosmos and expect a good harvest is probably August. If you wait any later than that and your cosmos may not have a chance to fully mature. Starting your cosmos indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Zone 8a the average date of last frost happens on March 15. We should expect an average low temperature of 10°F in the coldest months of winter.

Since the USDA zone info for Zone 8a is not always accurate our actual date of last frost is different every year. Half of the time in Zone 8a there is a last frost after March 15 so always be ready to protect your cosmos if we have a surprise late frost.

USDA Zone Info for Zone 8a

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)March 15
Average Date of First Frost (fall)November 15
Lowest Expected Low10°F
Highest Expected Low15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Zone 8a

You may be interested in our other planting guides for Zone 8a.