One of the best tools that you have as gardeners to help us estimate 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.

A way of determining when to plant skullcap is to check out the USDA zone info for Worthington.

Planting Calendar for Skullcap

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

Skullcap are not cold tolerant which tells us that you really should wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant skullcap in Worthington 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. If you are starting your skullcap indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Worthington the average date of last frost happens on May 15. In the coldest months of winter you can expect an average low temperature of -25°F.

Since the USDA zone info for Worthington is not always accurate the actual date of last frost changes from year to year. Half of the time in Worthington it frosts late in the year after May 15 so be sure to be ready to cover your skullcap in the event of a late frost.

USDA Zone Info for Worthington

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Worthington

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