The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's a good idea to figure out when it's the best time to plant purple rock cress by reviewing the USDA zone info for Douglas.

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 quite a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant purple rock cress in Douglas 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 purple rock cress and expect a good harvest is probably August. Any later than that and your purple rock cress may not have a chance to fully mature. 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

On average the last frost when the weather gets warmer is on May 15 in Douglas. It might get as low as -25°F during the coldest months of winter.

Since the USDA zone info for Douglas is an average the actual date of last frost is different every year. Half of the time in Douglas you get a frost after May 15 so always be ready to protect your purple rock cress if you have a surprise late frost.

USDA Zone Info for Douglas

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Douglas

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