One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You can figure out when it's a good idea to plant purple rock cress in Umatilla by reviewing the USDA zone info.

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.

You can plant purple rock cress earlier in the year because they do well in cold.

The earliest that you can plant purple rock cress in Umatilla 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 really do well. Starting your purple rock cress indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Umatilla. In the coldest months of winter you should expect an average low temperature of 5°F.

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

USDA Zone Info for Umatilla

Here is the info for USDA Zone 7b.

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

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

Plants to Grow in Umatilla

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