One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first chance to plant cardinal flower in Thief River Falls should be figured out by using the USDA zone info.

Planting Calendar for Cardinal Flower

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

Since cardinal flower are not cold tolerant it's necessary to wait until after the last frost before you can plant them.

The earliest that you can plant cardinal flower 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 cardinal flower and expect a good harvest is probably August. You probably don't want to wait any later than that or else your cardinal flower may not have a chance to grow to maturity. Starting your cardinal flower indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average all chance of frost has passed is on May 15 in Thief River Falls. It might get as low as -35°F during the coldest months of winter.

It's important to remember that USDA zone info for Thief River Falls is an average and the actual date of last frost changes from year to year. Half of the time in Thief River Falls you get a frost after May 15 so just be sure to be ready to protect your cardinal flower if you have a 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.