The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By using the USDA zone info for Iron Mountain it's possible to determine when you can plant skullcap.

Planting Calendar for Skullcap

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

Since skullcap are not cold tolerant you must wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant skullcap in Iron Mountain 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. If you wait any later than that and 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 little bit earlier.

Last Frost Date

In Iron Mountain the average date of last frost happens on May 15. You can expect an average low temperature of -30°F in the coldest months of winter.

It's important to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Iron Mountain and it changes from year to year. Since half of the time in Iron Mountain you get a frost after May 15 be ready to protect your skullcap in the event of one of those late frosts.

USDA Zone Info for Iron Mountain

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Iron Mountain

You may be interested in your other planting guides for Iron Mountain.