One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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 making a decision about when to plant rock cress is to use the USDA zone info for Zone 9a.

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 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 Zone 9a 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. Any later than that and your rock cress may not have a chance to really do well. If you are starting your rock cress indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost is on February 15 in Zone 9a. In the coldest months of winter you should expect an average low temperature of 20°F.

Always keep in mind that USDA zone info for Zone 9a is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Zone 9a you get surprised by a frost after February 15 so always be ready to protect your rock cress if you have a late frost.

USDA Zone Info for Zone 9a

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Zone 9a

You may be interested in your other planting guides for Zone 9a.