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.

The USDA zone info for Washington can be reffered to in order to estimate 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 one of those plants that can tolerate quite a bit of cold weather which tells us that you can start planting them much earlier than other plants that might not handle the cold.

The earliest that you can plant rock cress in Washington is February. However, you really should wait until March 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 September. Any later than that and 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 April 15 in Washington. In the coldest months of winter you can expect an average low temperature of -10°F.

Since the USDA zone info for Washington is just an average the actual date of last frost will vary from year to year. Half of the time in Washington last frost occurs after April 15 so be sure to be ready to protect your rock cress if you have one of those late frosts.

USDA Zone Info for Washington

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Washington

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