One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of getting a good idea when it's possible to plant purple rock cress is to examine the USDA zone info for Arcata.

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 do ok in a bit of cold which tells us that you can plant them earlier in the year than other frost tender plants.

The earliest that you can plant purple rock cress in Arcata 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 purple rock cress and expect a good harvest is probably October. If you wait 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

In Arcata the average date of last frost happens on February 15. You can expect an average low temperature of 25°F in the coldest months of winter.

Since the USDA zone info for Arcata is not always accurate the actual date of last frost can change quite a bit from year to year. Since half of the time in Arcata there is a last frost after February 15 be ready to cover your purple rock cress in the event of a surprise late frost.

USDA Zone Info for Arcata

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 Arcata

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