Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of determining when it's a good idea to plant cosmos is to look at the USDA zone info for Mankato.

Planting Calendar for Cosmos

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

Cosmos tend to make it in some cold which tells us that you can plant them just a tiny bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant cosmos in Mankato is April. However, you really should wait until May 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. You probably don't want to wait any later than that or else your cosmos may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your cosmos indoors.

Last Frost Date

In Mankato the average date of last frost happens on May 15. In the coldest months of winter you should expect an average low temperature of -25°F.

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Mankato and it is different every year. Half of the time in Mankato there is a last frost after May 15 so always be ready to cover your cosmos if you have a late frost.

USDA Zone Info for Mankato

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

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

Plants to Grow in Mankato

You may be interested in your other planting guides for Mankato.