One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. 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 Harrisburg you should be able to estimate when to plant ageratum.

Planting Calendar for Ageratum

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

Since ageratum are not cold tolerant it's necessary to wait until after the last frost before you can plant them.

The earliest that you can plant ageratum in Harrisburg 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. Any later than that and your ageratum may not have a chance to really do well. If you are starting your ageratum indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Harrisburg the average date of last frost happens on April 15. You should expect an average low temperature of 5°F in the coldest months of winter.

Since the USDA zone info for Harrisburg is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Harrisburg you get surprised by a frost after April 15 be ready to cover your ageratum in the event of one of those late frosts.

USDA Zone Info for Harrisburg

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 Harrisburg

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