Before planting it is a good idea to find your USDA Zone info to estimate your garden 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 Francisco can be looked at to estimate when it's a good idea to plant fennel.

Planting Calendar for Fennel

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

Since fennel are very cold tolerant you can plant them quite a bit earlier in the year than more sensitive plants.

The earliest that you can plant fennel in San Francisco 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 fennel and expect a good harvest is probably October. If you wait any later than that and your fennel may not have a chance to really do well. You can get started a few weeks earlier by starting your fennel indoors.

Last Frost Date

In San Francisco the average date of last frost happens on January 31. It might get as low as 35°F during the coldest months of winter.

Since the USDA zone info for San Francisco is an average the actual date of last frost changes from year to year. Since half of the time in San Francisco you get surprised by a frost after January 31 be ready to cover your fennel in the event of a surprise 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.