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.

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

Planting Calendar for Tithonia

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

Since tithonia are not cold tolerant you have to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant tithonia in Jefferson 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 grow to maturity. You can get started a few weeks earlier by starting your tithonia indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Jefferson. In the coldest months of winter you should expect an average low temperature of -20°F.

Since the USDA zone info for Jefferson may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Jefferson there is a last frost after April 15 so always be ready to cover your tithonia in the event of one of those late frosts.

USDA Zone Info for Jefferson

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 Jefferson

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