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.

One way of figuring out when it's possible to plant purple rock cress is to consult the USDA zone info for Palo Alto.

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 are very cold tolerant.

The earliest that you can plant purple rock cress in Palo Alto 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. Any later than that and your purple rock cress may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your purple rock cress indoors.

Last Frost Date

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

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Palo Alto and it can change quite a bit from year to year. Half of the time in Palo Alto it frosts late in the year after February 15 so make sure that you are prepared to cover your purple rock cress if you have a late frost.

USDA Zone Info for Palo Alto

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 Palo Alto

You may be interested in your other planting guides for Palo Alto.