One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of estimating when it's possible to plant purple rock cress is to refer to the USDA zone info for Chaska.

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 do ok in cold weather which means that you can plant them quite a bit earlier in the year than other frost tender plants.

The earliest that you can plant purple rock cress in Chaska 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. If you wait any later than that and your purple rock cress may not have a chance to grow to maturity. Starting your purple rock cress indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is May 15 in Chaska. It might get as low as -25°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Chaska may not be accurate from year to year and the actual date of last frost is different every year. Half of the time in Chaska you get surprised by a frost after May 15 so be sure to be ready to protect your purple rock cress if you have a surprise late frost.

USDA Zone Info for Chaska

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 Chaska

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