Before planting it is a good idea to find your USDA Zone info to estimate 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.

By checking out the USDA zone info for Renton you should be able to figure out when you can plant rock cress.

Planting Calendar for Rock Cress

Frost tolerance for rock cress:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

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

The earliest that you can plant rock cress in Renton 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 rock cress and expect a good harvest is probably September. Any later than that and your rock cress may not have a chance to fully mature. If you are starting your rock cress indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on March 15 in Renton. You should expect an average low temperature of 15°F in the coldest months of winter.

Remember that USDA zone info for Renton is just an average and the actual date of last frost is different every year. Since half of the time in Renton you get a frost after March 15 be ready to protect your rock cress in the event of a late frost.

USDA Zone Info for Renton

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 Renton

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