Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By referring to the USDA zone info for Rapid City you should be able to figure out when it's possible to plant tithonia.

Planting Calendar for Tithonia

Frost tolerance for tithonia:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since tithonia are not cold tolerant you must wait until after the last frost before you can plant them.

The earliest that you can plant tithonia in Rapid City 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 really do well. You can get started a couple of weeks earlier by starting your tithonia indoors.

Last Frost Date

In Rapid City the average date of last frost happens on April 15. You can expect an average low temperature of -20°F in the coldest months of winter.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Rapid City and it can change quite a bit from year to year. Half of the time in Rapid City it frosts late in the year after April 15 so be sure to be ready to cover your tithonia if you have a late frost.

USDA Zone Info for Rapid City

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Rapid City

You may be interested in your other planting guides for Rapid City.