Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Thief River Falls can be read to determine when it's possible to plant hollyhocks.

Planting Calendar for Hollyhocks

Frost tolerance for hollyhocks:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Hollyhocks do well in moderate cold which tells us that you can plant them earlier than more sensitive plants.

The earliest that you can plant hollyhocks in Thief River Falls is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant hollyhocks and expect a good harvest is probably August. If you wait any later than that and your hollyhocks may not have a chance to grow to maturity. Starting your hollyhocks indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

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

Since the USDA zone info for Thief River Falls is an average the actual date of last frost changes from year to year. Since half of the time in Thief River Falls last frost occurs after May 15 be ready to cover your hollyhocks in the event of 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.