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

You will be able to estimate when it's the best time to plant periwinkles by using the USDA zone info for San Bruno.

Planting Calendar for Periwinkles

Frost tolerance for periwinkles:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since periwinkles require warm weather it's important to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant periwinkles in San Bruno is February. However, you really should wait until March 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 grow to maturity. You can get started a few weeks earlier by starting your periwinkles indoors.

Last Frost Date

The average date of last frost is January 31 in San Bruno. You should expect an average low temperature of 30°F in the coldest months of winter.

Remember that USDA zone info for San Bruno is not always accurate and the actual date of last frost changes from year to year. Since half of the time in San Bruno you get a frost after January 31 be ready to cover your periwinkles if you have one of those late frosts.

USDA Zone Info for San Bruno

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in San Bruno

You may be interested in your other planting guides for San Bruno.