Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to determine when to plant periwinkles by referring to the USDA zone info for Pacific.

Planting Calendar for Periwinkles

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

Periwinkles do not do well in cold weather which tells us that you have 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 Pacific is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant periwinkles and expect a good harvest is probably August. Any later than that and 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 Pacific the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -10°F.

Since the USDA zone info for Pacific is just an average the actual date of last frost will vary from year to year. Half of the time in Pacific last frost occurs after April 15 so be sure to be ready to cover your periwinkles in the event of a late frost.

USDA Zone Info for Pacific

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Pacific

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