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

One way of figuring out when it's possible to plant geranium is to refer to the USDA zone info for Portola Valley.

Planting Calendar for Geranium

Frost tolerance for geranium:	Not tolerant of frost.
When to plant:	After the last frost.

Since geranium are not cold tolerant it is necessary to wait until after the last frost has passed before you can plant them.

The earliest that you can plant geranium in Portola Valley is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant geranium and expect a good harvest is probably September. Any later than that and your geranium may not have a chance to grow to maturity. You can get started a little bit earlier by starting your geranium indoors.

Last Frost Date

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

Since the USDA zone info for Portola Valley is an average the actual date of last frost changes from year to year. Half of the time in Portola Valley last frost occurs after January 31 so make sure that you are prepared to cover your geranium if you have 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.