One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Zone 1a can be reffered to in order to determine when 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.

Since purple rock cress do well in cold you can plant them a lot earlier in the year than more sensitive plants.

The earliest that you can plant purple rock cress in Zone 1a is May. However, you really should wait until June 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 July. Any later than that and your purple rock cress may not have a chance to really do well. If you are starting your purple rock cress indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

The average date of last frost is June 15 in Zone 1a. You can expect an average low temperature of -60°F in the coldest months of winter.

Since the USDA zone info for Zone 1a is an average the actual date of last frost is different every year. Since half of the time in Zone 1a it frosts late in the year after June 15 be ready to cover your purple rock cress in the event of a late frost.

USDA Zone Info for Zone 1a

Here is the info for USDA Zone 1a.

Average Date of Last Frost (spring)	June 15
Average Date of First Frost (fall)	July 15
Lowest Expected Low	-60°F
Highest Expected Low	-55°F

This means that on a really cold year, the coldest it will get is -60°F. On most years you should be prepared to experience lows near -55°F.

Plants to Grow in Zone 1a

You may be interested in your other planting guides for Zone 1a.