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.

In International Falls you can figure out when to plant tithonia by referring to the USDA zone info.

Planting Calendar for Tithonia

Frost tolerance for tithonia:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Tithonia do not do well in cold weather which means that it's necessary to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant tithonia 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 tithonia and expect a good harvest is probably August. Any later than that and your tithonia may not have a chance to fully mature. You can get started a few weeks earlier by starting your tithonia indoors.

Last Frost Date

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

Since the USDA zone info for International Falls is just an average the actual date of last frost will vary from year to year. Since half of the time in International Falls last frost occurs after May 15 be ready to protect your tithonia if you have a 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.