Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Dickinson can be looked at to estimate when it's possible to plant periwinkles.

Planting Calendar for Periwinkles

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

You should not plant periwinkles until after the last frost because they do not do well in cold weather.

The earliest that you can plant periwinkles in Dickinson is May. However, you really should wait until June 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 really do well. Starting your periwinkles indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is May 15 in Dickinson. In the coldest months of winter you can expect an average low temperature of -30°F.

Just be sure to remember that USDA zone info for Dickinson may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Half of the time in Dickinson you get surprised by a frost after May 15 so make sure that you are prepared to cover your periwinkles in the event of a surprise late frost.

USDA Zone Info for Dickinson

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Dickinson

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