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.

By referring to the USDA zone info for Chehalis you should be able to figure out when to plant purple rock cress.

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.

Since purple rock cress are very cold tolerant you can plant them much earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant purple rock cress in Chehalis 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 purple rock cress and expect a good harvest is probably September. Any later than that and your purple rock cress may not have a chance to really do well. You can get started a few weeks earlier by starting your purple rock cress indoors.

Last Frost Date

The average date of last frost is March 15 in Chehalis. In the coldest months of winter you should expect an average low temperature of 10°F.

Just be sure to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Chehalis and it is different every year. Half of the time in Chehalis last frost occurs after March 15 so be sure to be ready to protect your purple rock cress if you have a surprise late frost.

USDA Zone Info for Chehalis

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°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 15°F.

Plants to Grow in Chehalis

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