One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Thief River Falls can be reviewed to determine when to plant skullcap.

Planting Calendar for Skullcap

Frost tolerance for skullcap:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Since skullcap do not do well in cold weather it is necessary to wait until after the last frost before you can plant them.

The earliest that you can plant skullcap in Thief River Falls is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant skullcap and expect a good harvest is probably August. You probably don't want to wait any later than that or else your skullcap may not have a chance to really do well. You can get started a little bit earlier by starting your skullcap indoors.

Last Frost Date

On average all chance of frost has passed is on May 15 in Thief River Falls. It might get as low as -35°F during the coldest months of winter.

Since the USDA zone info for Thief River Falls is not always accurate the actual date of last frost can change quite a bit from year to year. Half of the time in Thief River Falls there is a last frost after May 15 so just be sure to be ready to protect your skullcap if you have a late frost.

USDA Zone Info for Thief River Falls

Here is the info for USDA Zone 3b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-35°F
Highest Expected Low	-30°F

This means that on a really cold year, the coldest it will get is -35°F. On most years you should be prepared to experience lows near -30°F.

Plants to Grow in Thief River Falls

You may be interested in your other planting guides for Thief River Falls.