One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A common way of figuring out when it's possible to plant rock cress is to consult the USDA zone info for Zimmerman.

Planting Calendar for Rock Cress

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

You can plant rock cress much earlier in the year because they are very cold tolerant.

The earliest that you can plant rock cress in Zimmerman 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 grow to maturity. Starting your rock cress indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Zimmerman the average date of last frost happens on May 15. It might get as low as -30°F during the coldest months of winter.

Since the USDA zone info for Zimmerman is not always accurate the actual date of last frost changes from year to year. Half of the time in Zimmerman there is a last frost after May 15 so make sure that you are prepared to cover your rock cress if you have one of those late frosts.

USDA Zone Info for Zimmerman

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 Zimmerman

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