One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first chance to plant primula in Sonoma should be determined by referring to the USDA zone info.

Planting Calendar for Primula

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

Primula are one of those plants that can tolerate quite a bit of cold weather which tells us that you can start planting them much earlier than other plants that might not handle the cold.

The earliest that you can plant primula in Sonoma 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 primula and expect a good harvest is probably October. Any later than that and your primula may not have a chance to fully mature. You can get started a few weeks earlier by starting your primula indoors.

Last Frost Date

The average date of last frost is February 15 in Sonoma. You should expect an average low temperature of 25°F in the coldest months of winter.

Remember that USDA zone info for Sonoma is an average and the actual date of last frost is different every year. Half of the time in Sonoma you get a frost after February 15 so make sure that you are ready to cover your primula if you have a late frost.

USDA Zone Info for Sonoma

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 Sonoma

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