One of the best tools that you have as gardeners to help us estimate your gardening schedule is the 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.

In Rialto you can figure out when you can plant purple rock cress by looking at 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.

Purple Rock Cress do well in cold weather which means that you can plant them earlier in the year than more sensitive plants.

The earliest that you can plant purple rock cress in Rialto 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. Starting your purple rock cress indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost is on January 31 in Rialto. It might get as low as 30°F during the coldest months of winter.

Remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Rialto and it can change quite a bit from year to year. Since half of the time in Rialto last frost occurs after January 31 be ready to protect your purple rock cress if you have a late frost.

USDA Zone Info for Rialto

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in Rialto

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