One of the first steps you take when you are determining 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.

It's a good idea to estimate when it's the best time to plant zinnia by checking out the USDA zone info for Petersburg.

Planting Calendar for Zinnia

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

Zinnia require warm weather which means that it's necessary to wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant zinnia in Petersburg 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. You probably don't want to wait any later than that or else your zinnia may not have a chance to fully mature. If you are starting your zinnia indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average all chance of frost has passed is on April 15 in Petersburg. In the coldest months of winter you should expect an average low temperature of 5°F.

It's important to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Petersburg and it will vary from year to year. Since half of the time in Petersburg there is a last frost after April 15 be ready to cover your zinnia if you have a surprise late frost.

USDA Zone Info for Petersburg

Here is the info for USDA Zone 7b.

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

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in Petersburg

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