Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first chance to plant ageratum in Billings can be determined by referring to the USDA zone info.

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 you have to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant ageratum in Billings 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. 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

On average the last frost when the weather gets warmer is on May 15 in Billings. In the coldest months of winter you can expect an average low temperature of -25°F.

Always keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Billings and it is different every year. Half of the time in Billings you get surprised by a frost after May 15 so be sure to be ready to protect your ageratum in the event of one of those late frosts.

USDA Zone Info for Billings

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 Billings

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