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.

It's possible to determine when it's a good idea to plant liatris by looking at the USDA zone info for Rockville.

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 one of those plants that can tolerate quite a bit of cold weather you can plant them earlier in the year than other frost tender plants.

The earliest that you can plant liatris in Rockville 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. Any later than that and your liatris may not have a chance to fully mature. You can get started a little bit earlier by starting your liatris indoors.

Last Frost Date

In Rockville the average date of last frost happens on April 15. You can expect an average low temperature of 0°F in the coldest months of winter.

Always keep in mind that USDA zone info for Rockville is an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Rockville you get surprised by a frost after April 15 be ready to protect your liatris in the event of a surprise late frost.

USDA Zone Info for Rockville

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Rockville

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