One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Spirit Lake you can figure out when it's possible to plant periwinkles by reviewing the USDA zone info.

Planting Calendar for Periwinkles

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

Since periwinkles do not do well in cold weather you need to wait until after the last frost has passed before you can plant them.

The earliest that you can plant periwinkles in Spirit Lake 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. You probably don't want to wait any later than that or else your periwinkles may not have a chance to fully mature. You can get started a little bit earlier by starting your periwinkles indoors.

Last Frost Date

The average date of last frost is April 15 in Spirit Lake. In the coldest months of winter you can expect an average low temperature of -20°F.

Keep in mind that USDA zone info for Spirit Lake is an average and the actual date of last frost is different every year. Half of the time in Spirit Lake last frost occurs after April 15 so just be sure to be ready to protect your periwinkles if you have one of those late frosts.

USDA Zone Info for Spirit Lake

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Spirit Lake

You may be interested in your other planting guides for Spirit Lake.