The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Grand Forks can be used to estimate when to plant skullcap.

Planting Calendar for Skullcap

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

Skullcap are not cold tolerant which tells us that it's necessary to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant skullcap in Grand Forks 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 fully mature. You can get started a couple of weeks earlier by starting your skullcap indoors.

Last Frost Date

The average date of last frost is May 15 in Grand Forks. In the coldest months of winter you can expect an average low temperature of -30°F.

Always keep in mind that USDA zone info for Grand Forks is not always accurate and the actual date of last frost will vary from year to year. Half of the time in Grand Forks it frosts late in the year after May 15 so always be ready to cover your skullcap in the event of a late frost.

USDA Zone Info for Grand Forks

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 Grand Forks

You may be interested in your other planting guides for Grand Forks.