The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By checking out the USDA zone info for Port Townsend it's possible to estimate 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.

Purple Rock Cress tend to make it in pretty solid cold which tells us that you can plant them quite a bit earlier in the year than more sensitive plants.

The earliest that you can plant purple rock cress in Port Townsend 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. You probably don't want to wait any later than that or else your purple rock cress may not have a chance to grow to maturity. Starting your purple rock cress indoors is a great way to get them started a few weeks earlier.

Last Frost Date

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

Since the USDA zone info for Port Townsend is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Port Townsend there is a last frost after March 15 so always be ready to protect your purple rock cress in the event of a late frost.

USDA Zone Info for Port Townsend

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°F

This means that on a really cold year, the coldest it will get is 15°F. On most years you should be prepared to experience lows near 20°F.

Plants to Grow in Port Townsend

You may be interested in your other planting guides for Port Townsend.