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.

In San Francisco you can estimate when it's a good idea to plant tomatos by checking out the USDA zone info.

Planting Calendar for Tomatos

Frost tolerance for tomatos:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

It's probably not a good idea to plant tomatos until after all chance of frost has passed because they are not cold tolerant.

The earliest that you can plant tomatos in San Francisco 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 tomatos and expect a good harvest is probably September. Any later than that and your tomatos may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your tomatos indoors.

Last Frost Date

In San Francisco the average date of last frost happens on January 31. You should expect an average low temperature of 35°F in the coldest months of winter.

Remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for San Francisco and it can change quite a bit from year to year. Since half of the time in San Francisco last frost occurs after January 31 be ready to cover your tomatos in the event of a late frost.

USDA Zone Info for San Francisco

Here is the info for USDA Zone 10b.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	35°F
Highest Expected Low	40°F

This means that on a really cold year, the coldest it will get is 35°F. On most years you should be prepared to experience lows near 40°F.

Plants to Grow in San Francisco

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