The USDA Zone info is a great tool for gardeners to help us figure out 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 can determine when it's the best time to plant blue throatwort in Petersburg by using the USDA zone info.

Planting Calendar for Blue Throatwort

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

You should not plant blue throatwort until after the last frost because they are not cold tolerant.

The earliest that you can plant blue throatwort in Petersburg 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 blue throatwort and expect a good harvest is probably August. Any later than that and your blue throatwort may not have a chance to really do well. Starting your blue throatwort 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 Petersburg. You can expect an average low temperature of 5°F in the coldest months of winter.

Since the USDA zone info for Petersburg is an average the actual date of last frost changes from year to year. Half of the time in Petersburg there is a last frost after April 15 so just be sure to be ready to protect your blue throatwort if you have a surprise late frost.

USDA Zone Info for Petersburg

Here is the info for USDA Zone 7b.

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

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

Plants to Grow in Petersburg

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