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

The earliest that you can plant ageratum in Watertown can be figured out by reviewing the USDA zone info.

Planting Calendar for Ageratum

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

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

The earliest that you can plant ageratum in Watertown 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. Any later than that and your ageratum may not have a chance to grow to maturity. You can get started a little bit earlier by starting your ageratum indoors.

Last Frost Date

On average all chance of frost has passed is on May 15 in Watertown. You should expect an average low temperature of -25°F in the coldest months of winter.

It's important to remember that USDA zone info for Watertown is just an average and the actual date of last frost is different every year. Half of the time in Watertown it frosts late in the year after May 15 so make sure that you are prepared to protect your ageratum if you have one of those late frosts.

USDA Zone Info for Watertown

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 Watertown

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