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.

One way of getting a good idea when it's the best time to plant rock cress is to use the USDA zone info for Philadelphia.

Planting Calendar for Rock Cress

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

Rock Cress are one of those plants that can tolerate quite a bit of cold weather which means that you can get them planted much earlier than other plants that might not handle the cold.

The earliest that you can plant rock cress in Philadelphia 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 rock cress and expect a good harvest is probably September. Any later than that and your rock cress may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your rock cress indoors.

Last Frost Date

In Philadelphia the average date of last frost happens on April 15. It might get as low as 0°F during the coldest months of winter.

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Philadelphia and it will vary from year to year. Since half of the time in Philadelphia you get a frost after April 15 be ready to cover your rock cress in the event of a surprise late frost.

USDA Zone Info for Philadelphia

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 Philadelphia

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