The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first opportunity to plant periwinkles in International Falls should be determined by reviewing the USDA zone info.

Planting Calendar for Periwinkles

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

It's probably a bad idea to plant periwinkles until after the last frost has passed because they do not do well in cold weather.

The earliest that you can plant periwinkles in International Falls 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. If you wait any later than that and your periwinkles may not have a chance to really do well. You can get started a few weeks earlier by starting your periwinkles indoors.

Last Frost Date

On average the last frost has passed is on May 15 in International Falls. It might get as low as -40°F during the coldest months of winter.

Since the USDA zone info for International Falls may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in International Falls it frosts late in the year after May 15 be ready to cover your periwinkles if you have a late frost.

USDA Zone Info for International Falls

Here is the info for USDA Zone 3a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-40°F
Highest Expected Low	-35°F

This means that on a really cold year, the coldest it will get is -40°F. On most years you should be prepared to experience lows near -35°F.

Plants to Grow in International Falls

You may be interested in your other planting guides for International Falls.