Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By checking out the USDA zone info for Hannibal it's possible to estimate when you can plant zinnia.

Planting Calendar for Zinnia

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

It's a bad idea to plant zinnia until after the last frost because they are not cold tolerant.

The earliest that you can plant zinnia in Hannibal 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 zinnia and expect a good harvest is probably August. Any later than that and your zinnia may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your zinnia indoors.

Last Frost Date

The average date of last frost is April 15 in Hannibal. You can expect an average low temperature of -10°F in the coldest months of winter.

Keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Hannibal and it will vary from year to year. Half of the time in Hannibal last frost occurs after April 15 so just be sure to be ready to cover your zinnia if you have a surprise late frost.

USDA Zone Info for Hannibal

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°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 -5°F.

Plants to Grow in Hannibal

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