The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

It's possible to determine when you can plant periwinkles by using the USDA zone info for Yelm.

Planting Calendar for Periwinkles

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

Periwinkles require warm weather which tells us that it's important to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant periwinkles in Yelm 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 fully mature. If you are starting your periwinkles indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Yelm the average date of last frost happens on March 15. In the coldest months of winter you can expect an average low temperature of 10°F.

Since the USDA zone info for Yelm is just an average the actual date of last frost changes from year to year. Since half of the time in Yelm you get a frost after March 15 be ready to cover your periwinkles if you have a surprise late frost.

USDA Zone Info for Yelm

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°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 15°F.

Plants to Grow in Yelm

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