One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You will be able to estimate when it's possible to plant liatris by using the USDA zone info for Caribou.

Planting Calendar for Liatris

Frost tolerance for liatris:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Liatris tend to make it in quite a bit of cold which tells us that you can plant them quite a bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant liatris in Caribou 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 liatris and expect a good harvest is probably August. Any later than that and your liatris may not have a chance to really do well. You can get started a little bit earlier by starting your liatris indoors.

Last Frost Date

On average the last frost is on May 15 in Caribou. It might get as low as -30°F during the coldest months of winter.

Since the USDA zone info for Caribou is not always accurate the actual date of last frost changes from year to year. Since half of the time in Caribou you get a frost after May 15 be ready to protect your liatris if you have a surprise 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.