The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By looking at the USDA zone info for Northfield it's a good idea to figure out when to plant ageratum.

Planting Calendar for Ageratum

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

Since ageratum require warm weather it is necessary to wait until after the last frost before you can plant them.

The earliest that you can plant ageratum in Northfield is May. However, you really should wait until June 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

The average date of last frost is May 15 in Northfield. In the coldest months of winter you can expect an average low temperature of -25°F.

Since the USDA zone info for Northfield is just an average the actual date of last frost is different every year. Half of the time in Northfield you get a frost after May 15 so make sure that you are prepared to protect your ageratum if you have a surprise late frost.

USDA Zone Info for Northfield

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Northfield

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