One of the first steps you take when you are figuring out 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.

You can figure out when it's possible to plant skullcap in Johnston by looking at the USDA zone info.

Planting Calendar for Skullcap

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

It's probably not a good idea to plant skullcap until after all chance of frost has passed because they require warm weather.

The earliest that you can plant skullcap in Johnston 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 grow to maturity. Starting your skullcap indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Johnston. It might get as low as -20°F during the coldest months of winter.

Since the USDA zone info for Johnston is just an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Johnston there is a last frost after April 15 be ready to protect your skullcap in the event of a surprise late frost.

USDA Zone Info for Johnston

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Johnston

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