One of the best tools that you have as gardeners to help us estimate 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.

The USDA zone info for Portola Valley can be reffered to in order to estimate when to plant radicchio.

Planting Calendar for Radicchio

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

Radicchio do well in moderate cold which tells us that you can plant them earlier than plants that are more sensitive to the cold.

The earliest that you can plant radicchio in Portola Valley 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 grow to maturity. If you are starting your radicchio indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

On average all chance of frost has passed is on January 31 in Portola Valley. In the coldest months of winter you should expect an average low temperature of 30°F.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Portola Valley and it changes from year to year. Half of the time in Portola Valley you get a frost after January 31 so just be sure to be ready to cover your radicchio in the event of a late frost.

USDA Zone Info for Portola Valley

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 Portola Valley

You may be interested in your other planting guides for Portola Valley.