The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The best time to plant sunflowers in International Falls should be figured out by looking at the USDA zone info.

Planting Calendar for Sunflowers

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

Sunflowers do not do well in cold weather which means that you must wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant sunflowers 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 sunflowers and expect a good harvest is probably August. You probably don't want to wait any later than that or else your sunflowers may not have a chance to really do well. You can get started a couple of weeks earlier by starting your sunflowers indoors.

Last Frost Date

On average the last frost is on May 15 in International Falls. In the coldest months of winter you should expect an average low temperature of -40°F.

Since the USDA zone info for International Falls is not always accurate the actual date of last frost can change quite a bit 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 sunflowers in the event of a surprise 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.