The USDA Zone info is a great tool for gardeners to help us determine 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.

It's possible to figure out when it's possible to plant liatris by using the USDA zone info for Petersburg.

Planting Calendar for Liatris

Frost tolerance for liatris:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since liatris are very cold tolerant you can plant them earlier in the year than other frost tender plants.

The earliest that you can plant liatris in Petersburg is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant liatris and expect a good harvest is probably September. You probably don't want to wait any later than that or else your liatris may not have a chance to really do well. Starting your liatris indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Petersburg. In the coldest months of winter you can expect an average low temperature of 5°F.

Since the USDA zone info for Petersburg is just an average the actual date of last frost is different every year. Half of the time in Petersburg it frosts late in the year after April 15 so make sure that you are ready to cover your liatris in the event of a 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.