One of the best tools that you have as gardeners to help us estimate 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.

By using the USDA zone info for Merrill you will be able to figure out when to plant rock cress.

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 are very cold tolerant which tells us that you can plant them a quite a bit earlier than more sensitive plants.

The earliest that you can plant rock cress in Merrill 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. You can get started a few weeks earlier by starting your rock cress indoors.

Last Frost Date

The average date of last frost is May 15 in Merrill. In the coldest months of winter you should expect an average low temperature of -30°F.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Merrill and it will vary from year to year. Since half of the time in Merrill last frost occurs after May 15 be ready to protect your rock cress if you have a late frost.

USDA Zone Info for Merrill

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 Merrill

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