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

The USDA zone info for Petersburg should be looked at to determine when to plant ageratum.

Planting Calendar for Ageratum

Frost tolerance for ageratum:	Not tolerant of frost.
When to plant:	After the last frost has passed.

You should not plant ageratum until after the last frost has passed because they do not do well in cold weather.

The earliest that you can plant ageratum 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 ageratum and expect a good harvest is probably August. If you wait any later than that and your ageratum may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your ageratum indoors.

Last Frost Date

On average the last frost is on April 15 in Petersburg. You can expect an average low temperature of 5°F in the coldest months of winter.

Always keep in mind that USDA zone info for Petersburg is not always accurate and the actual date of last frost is different every year. Half of the time in Petersburg it frosts late in the year after April 15 so be sure to be ready to protect your ageratum if you have one of those late frosts.

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.