The USDA Zone info is a great tool for gardeners to help us determine 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.

You can estimate when to plant periwinkles in Wyoming by checking out 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.

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

The earliest that you can plant periwinkles in Wyoming 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. If you wait 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 Wyoming the average date of last frost happens on April 15. It might get as low as -15°F during the coldest months of winter.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Wyoming and it can change quite a bit from year to year. Half of the time in Wyoming you get surprised by a frost after April 15 so make sure that you are prepared to protect your periwinkles if you have one of those late frosts.

USDA Zone Info for Wyoming

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Wyoming

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