One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Sonora you can figure out when it's the best time to plant radicchio by checking out the USDA zone info.

Planting Calendar for Radicchio

Frost tolerance for radicchio:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Radicchio are moderately cold tolerant which means that you can start planting them earlier than other frost tender plants.

The earliest that you can plant radicchio in Sonora 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 radicchio and expect a good harvest is probably October. Any later than that and your radicchio may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your radicchio indoors.

Last Frost Date

The average date of last frost is February 15 in Sonora. You should expect an average low temperature of 20°F in the coldest months of winter.

Since the USDA zone info for Sonora is an average the actual date of last frost is different every year. Half of the time in Sonora last frost occurs after February 15 so just be sure to be ready to protect your radicchio in the event of a surprise late frost.

USDA Zone Info for Sonora

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 Sonora

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