Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Portland you can estimate when you can plant rock cress by looking at the USDA zone info.

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 ok in a bit of cold which tells us that you can plant them quite a bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant rock cress in Portland is January. However, you really should wait until February 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 October. You probably don't want to wait any later than that or else your rock cress may not have a chance to fully mature. You can get started a few weeks earlier by starting your rock cress indoors.

Last Frost Date

The average date of last frost is February 15 in Portland. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for Portland is an average the actual date of last frost will vary from year to year. Since half of the time in Portland it frosts late in the year after February 15 be ready to protect your rock cress if you have a surprise late frost.

USDA Zone Info for Portland

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°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 30°F.

Plants to Grow in Portland

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