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

In International Falls you can determine when it's possible to plant skullcap by looking at the USDA zone info.

Planting Calendar for Skullcap

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

Since skullcap are not cold tolerant it is necessary to wait until after the last frost before you can plant them.

The earliest that you can plant skullcap in International 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. Any later than that and your skullcap may not have a chance to fully mature. You can get started a little bit earlier by starting your skullcap indoors.

Last Frost Date

The average date of last frost is May 15 in International Falls. You should expect an average low temperature of -40°F in the coldest months of winter.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for International Falls and it will vary from year to year. Half of the time in International Falls there is a last frost after May 15 so make sure that you are prepared to cover your skullcap if you have one of those late frosts.

USDA Zone Info for International Falls

Here is the info for USDA Zone 3a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-40°F
Highest Expected Low	-35°F

This means that on a really cold year, the coldest it will get is -40°F. On most years you should be prepared to experience lows near -35°F.

Plants to Grow in International Falls

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