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

It's a good idea to determine when it's a good idea to plant cosmos by referring to the USDA zone info for Caribou.

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 are barely cold tolerant which means that you can get them planted just a bit earlier than other plants that might not handle the cold.

The earliest that you can plant cosmos in Caribou 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. 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 little bit earlier.

Last Frost Date

In Caribou the average date of last frost happens on May 15. You should expect an average low temperature of -30°F in the coldest months of winter.

Remember that USDA zone info for Caribou may not be accurate from year to year and the actual date of last frost will vary from year to year. Half of the time in Caribou there is a last frost after May 15 so make sure that you are ready to cover your cosmos in the event of a late frost.

USDA Zone Info for Caribou

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°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 -25°F.

Plants to Grow in Caribou

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