The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By reviewing the USDA zone info for Portola Valley you should be able to determine when it's possible to plant spearmint.

Planting Calendar for Spearmint

Frost tolerance for spearmint:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

You can plant spearmint much earlier in the year because they are one of those plants that can tolerate quite a bit of cold weather.

The earliest that you can plant spearmint 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 spearmint and expect a good harvest is probably October. You probably don't want to wait any later than that or else your spearmint may not have a chance to grow to maturity. Starting your spearmint indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

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

Since the USDA zone info for Portola Valley is just an average the actual date of last frost will vary from year to year. Since half of the time in Portola Valley you get surprised by a frost after January 31 be ready to protect your spearmint if you have a surprise 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.