The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. 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 Palo Alto should be looked at to estimate when it's a good idea to plant sorrel.

Planting Calendar for Sorrel

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

You can plant sorrel just a bit earlier in the year because they do well in moderate cold.

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

Last Frost Date

In Palo Alto the average date of last frost happens on February 15. In the coldest months of winter you should expect an average low temperature of 25°F.

Just be sure to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Palo Alto and it is different every year. Half of the time in Palo Alto there is a last frost after February 15 so make sure that you are ready to cover your sorrel if you have one of those late frosts.

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.