One of the first steps you take when you are getting a good idea your gardening schedule is find your 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.

In Petaluma you can estimate when it's the best time to plant fennel by reviewing the USDA zone info.

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 one of those plants that can tolerate quite a bit of cold weather you can plant them earlier in the year than other plants that might not handle the cold.

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

Last Frost Date

The average date of last frost is February 15 in Petaluma. It might get as low as 25°F during the coldest months of winter.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Petaluma and it will vary from year to year. Since half of the time in Petaluma there is a last frost after February 15 be ready to cover your fennel if you have one of those late frosts.

USDA Zone Info for Petaluma

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 Petaluma

You may be interested in your other planting guides for Petaluma.