Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Belle Fourche can be read 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.

It's 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 Belle Fourche 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 fully mature. You can get started a few weeks earlier by starting your ageratum indoors.

Last Frost Date

On average the last frost is on May 15 in Belle Fourche. It might get as low as -25°F during the coldest months of winter.

Keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Belle Fourche and it will vary from year to year. Half of the time in Belle Fourche last frost occurs after May 15 so make sure that you are ready to protect your ageratum in the event of one of those late frosts.

USDA Zone Info for Belle Fourche

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 Belle Fourche

You may be interested in your other planting guides for Belle Fourche.