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.

A common way of figuring out when it's the best time to plant skullcap is to examine the USDA zone info for Thornton.

Planting Calendar for Skullcap

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

Skullcap require warm weather which tells us that you need to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant skullcap in Thornton is April. However, you really should wait until May 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. If you wait any later than that and 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

In Thornton the average date of last frost happens on April 15. It might get as low as -15°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Thornton is an average and the actual date of last frost will vary from year to year. Since half of the time in Thornton you get a frost after April 15 be ready to cover your skullcap in the event of a late frost.

USDA Zone Info for Thornton

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Thornton

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