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.

The USDA zone info for San Ramon should be looked at to estimate when it's the best time to plant petunias.

Planting Calendar for Petunias

Frost tolerance for petunias:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

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

The earliest that you can plant petunias in San Ramon 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 petunias and expect a good harvest is probably September. You probably don't want to wait any later than that or else your petunias may not have a chance to fully mature. If you are starting your petunias indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In San Ramon the average date of last frost happens on February 15. You can expect an average low temperature of 25°F in the coldest months of winter.

Just be sure to remember that USDA zone info for San Ramon is an average and the actual date of last frost changes from year to year. Half of the time in San Ramon you get a frost after February 15 so make sure that you are prepared to cover your petunias in the event of a late frost.

USDA Zone Info for San Ramon

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 San Ramon

You may be interested in your other planting guides for San Ramon.