Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Santa Rosa you can estimate when it's possible to plant periwinkles by reviewing the USDA zone info.

Planting Calendar for Periwinkles

Frost tolerance for periwinkles:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

You should not plant periwinkles until after the last frost because they require warm weather.

The earliest that you can plant periwinkles in Santa Rosa is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant periwinkles and expect a good harvest is probably September. You probably don't want to wait any later than that or else your periwinkles may not have a chance to fully mature. If you are starting your periwinkles indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Since the USDA zone info for Santa Rosa is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Santa Rosa you get surprised by a frost after February 15 so make sure that you are ready to cover your periwinkles in the event of one of those late frosts.

USDA Zone Info for Santa Rosa

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 Santa Rosa

You may be interested in your other planting guides for Santa Rosa.