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.

A way of making a decision about when you can plant periwinkles is to consult the USDA zone info for Willows.

Planting Calendar for Periwinkles

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

Periwinkles are not cold tolerant which tells us that you need to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant periwinkles in Willows 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. If you wait any later than that and your periwinkles may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your periwinkles indoors.

Last Frost Date

The average date of last frost is February 15 in Willows. It might get as low as 25°F during the coldest months of winter.

Keep in mind that USDA zone info for Willows may not be accurate from year to year and the actual date of last frost will vary from year to year. Half of the time in Willows last frost occurs after February 15 so make sure that you are prepared to cover your periwinkles in the event of one of those late frosts.

USDA Zone Info for Willows

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 Willows

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