The USDA Zone info is a great tool for gardeners to help us determine your gardening 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 Rock Falls should be looked at to estimate when it's the best time to plant tithonia.

Planting Calendar for Tithonia

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

It's probably not a good idea to plant tithonia until after the last frost has passed because they require warm weather.

The earliest that you can plant tithonia in Rock Falls is April. However, you really should wait until May 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. If you wait any later than that and your tithonia may not have a chance to fully mature. You can get started a little bit earlier by starting your tithonia indoors.

Last Frost Date

The average date of last frost is April 15 in Rock Falls. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Rock Falls is just an average the actual date of last frost is different every year. Since half of the time in Rock Falls it frosts late in the year after April 15 be ready to cover your tithonia if you have a surprise late frost.

USDA Zone Info for Rock Falls

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Rock Falls

You may be interested in your other planting guides for Rock Falls.