One of the best tools that you have as gardeners to help us estimate 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.

The USDA zone info for Manhattan should be looked at to figure out when it's the best time to plant ageratum.

Planting Calendar for Ageratum

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

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

The earliest that you can plant ageratum in Manhattan 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 really do well. Starting your ageratum indoors is a great way to get them started a little bit earlier.

Last Frost Date

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

Keep in mind that USDA zone info for Manhattan is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Manhattan you get a frost after April 15 so be sure to be ready to cover your ageratum in the event of one of those late frosts.

USDA Zone Info for Manhattan

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 Manhattan

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