One of the first steps you take when you are estimating 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.

You can figure out when it's possible to plant heliotrope in Thief River Falls by looking at the USDA zone info.

Planting Calendar for Heliotrope

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

Since heliotrope do not do well in cold weather it's necessary to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant heliotrope 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 heliotrope and expect a good harvest is probably August. You probably don't want to wait any later than that or else your heliotrope may not have a chance to grow to maturity. You can get started a little bit earlier by starting your heliotrope indoors.

Last Frost Date

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

Since the USDA zone info for Thief River Falls may not be accurate from year to year the actual date of last frost is different every year. Half of the time in Thief River Falls you get a frost after May 15 so make sure that you are ready to protect your heliotrope if you have one of those late frosts.

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.