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.

By looking at the USDA zone info for Charlestown you will be able to estimate when it's a good idea to plant purple rock cress.

Planting Calendar for Purple Rock Cress

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

Purple Rock Cress can survive in pretty solid cold which tells us that you can plant them earlier in the year than other frost tender plants.

The earliest that you can plant purple rock cress in Charlestown 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 purple rock cress and expect a good harvest is probably September. You probably don't want to wait any later than that or else your purple rock cress may not have a chance to fully mature. You can get started a few weeks earlier by starting your purple rock cress indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Charlestown. It might get as low as -5°F during the coldest months of winter.

Since the USDA zone info for Charlestown is not always accurate the actual date of last frost can change quite a bit from year to year. Half of the time in Charlestown there is a last frost after April 15 so make sure that you are prepared to cover your purple rock cress in the event of one of those late frosts.

USDA Zone Info for Charlestown

Here is the info for USDA Zone 6b.

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

Plants to Grow in Charlestown

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