One of the best tools that you have as gardeners to help us estimate 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 way of determining when you can plant rock cress is to refer to the USDA zone info for Billings.

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 do well in quite a bit of cold which tells us that you can plant them much earlier in the year than more sensitive plants.

The earliest that you can plant rock cress in Billings 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. If you wait any later than that and your rock cress may not have a chance to really do well. You can get started a couple of weeks earlier by starting your rock cress indoors.

Last Frost Date

On average all chance of frost has passed is on May 15 in Billings. You can expect an average low temperature of -25°F in the coldest months of winter.

Always keep in mind that USDA zone info for Billings is an average and the actual date of last frost is different every year. Since half of the time in Billings last frost occurs after May 15 be ready to protect your rock cress if you have one of those late frosts.

USDA Zone Info for Billings

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 Billings

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