Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The first chance to plant rock cress in Zone 4a should be estimated by looking at the USDA zone info.

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 do well in quite a bit of cold which tells us that you can plant them quite a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant rock cress in Zone 4a is March. However, you really should wait until April 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 August. You probably don't want to wait any later than that or else your rock cress may not have a chance to really do well. You can get started a few weeks earlier by starting your rock cress indoors.

Last Frost Date

On average all chance of frost has passed is on May 15 in Zone 4a. You should expect an average low temperature of -30°F in the coldest months of winter.

Since the USDA zone info for Zone 4a may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Zone 4a it frosts late in the year after May 15 so make sure that you are ready to protect your rock cress in the event of a surprise late frost.

USDA Zone Info for Zone 4a

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Zone 4a

You may be interested in your other planting guides for Zone 4a.