One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to determine when it's possible to plant tithonia by looking at the USDA zone info for Riverdale.

Planting Calendar for Tithonia

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

You can not plant tithonia until after the last frost because they are not cold tolerant.

The earliest that you can plant tithonia in Riverdale 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. You probably don't want to wait any later than that or else your tithonia may not have a chance to fully mature. Starting your tithonia indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on March 15 in Riverdale. In the coldest months of winter you should expect an average low temperature of 10°F.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Riverdale and it can change quite a bit from year to year. Since half of the time in Riverdale you get a frost after March 15 be ready to cover your tithonia if you have a late frost.

USDA Zone Info for Riverdale

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

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

Plants to Grow in Riverdale

You may be interested in your other planting guides for Riverdale.