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

One way of determining when it's a good idea to plant fennel is to look at the USDA zone info for Costa Mesa.

Planting Calendar for Fennel

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

Fennel tend to make it in cold weather which means that you can plant them quite a bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant fennel in Costa Mesa 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. Any later than that and your fennel may not have a chance to grow to maturity. If you are starting your fennel indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on January 31 in Costa Mesa. You should expect an average low temperature of 35°F in the coldest months of winter.

Since the USDA zone info for Costa Mesa is just an average the actual date of last frost will vary from year to year. Half of the time in Costa Mesa it frosts late in the year after January 31 so just be sure to be ready to cover your fennel in the event of a surprise late frost.

USDA Zone Info for Costa Mesa

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 Costa Mesa

You may be interested in your other planting guides for Costa Mesa.