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

The best time to plant periwinkles in Mill Valley can be estimated by looking at the USDA zone info.

Planting Calendar for Periwinkles

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

It's probably a bad idea to plant periwinkles until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant periwinkles in Mill Valley 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

In Mill Valley the average date of last frost happens on January 31. It might get as low as 30°F during the coldest months of winter.

It's important to remember that the actual date of last frost is an average because it is based on the USDA zone info for Mill Valley and it can change quite a bit from year to year. Since half of the time in Mill Valley it frosts late in the year after January 31 be ready to protect your periwinkles if you have a surprise late frost.

USDA Zone Info for Mill Valley

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 Mill Valley

You may be interested in your other planting guides for Mill Valley.