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.

You should be able to estimate when you can plant skullcap by reviewing the USDA zone info for South Portland.

Planting Calendar for Skullcap

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

Skullcap require warm weather which tells us that you must 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 South Portland 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. You probably don't want to wait any later than that or else 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 is on April 15 in South Portland. In the coldest months of winter you can expect an average low temperature of -15°F.

Since the USDA zone info for South Portland is not always accurate the actual date of last frost is different every year. Half of the time in South Portland there is a last frost after April 15 so be sure to be ready to cover your skullcap in the event of a surprise late frost.

USDA Zone Info for South Portland

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 South Portland

You may be interested in your other planting guides for South Portland.