One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The best time to plant skullcap in Chicago should be estimated by referring to the USDA zone info.

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 it is important to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant skullcap in Chicago 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. Any later than that and your skullcap may not have a chance to grow to maturity. Starting your skullcap indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Chicago. In the coldest months of winter you should expect an average low temperature of -10°F.

Remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Chicago and it will vary from year to year. Half of the time in Chicago it frosts late in the year after April 15 so always be ready to cover your skullcap in the event of a late frost.

USDA Zone Info for Chicago

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Chicago

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