One of the first steps you take when you are figuring out 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 Thief River Falls you can estimate when it's a good idea to plant iresene by looking at the USDA zone info.

Planting Calendar for Iresene

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

It's a bad idea to plant iresene until after all chance of frost has passed because they do not do well in cold weather.

The earliest that you can plant iresene in Thief River 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 iresene and expect a good harvest is probably August. Any later than that and your iresene may not have a chance to really do well. If you are starting your iresene indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Thief River Falls the average date of last frost happens on May 15. You should expect an average low temperature of -35°F in the coldest months of winter.

Keep in mind that USDA zone info for Thief River Falls is just an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Thief River Falls you get surprised by a frost after May 15 be ready to cover your iresene if you have a surprise late frost.

USDA Zone Info for Thief River Falls

Here is the info for USDA Zone 3b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-35°F
Highest Expected Low	-30°F

This means that on a really cold year, the coldest it will get is -35°F. On most years you should be prepared to experience lows near -30°F.

Plants to Grow in Thief River Falls

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