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 USDA zone info for Missoula should be reffered to in order to determine when it's a good idea 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.

Ageratum require warm weather which tells us that you must wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant ageratum in Missoula 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. Any later than that and your ageratum may not have a chance to fully mature. Starting your ageratum indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Missoula. In the coldest months of winter you can expect an average low temperature of -15°F.

Remember that USDA zone info for Missoula is an average and the actual date of last frost is different every year. Half of the time in Missoula you get a frost after April 15 so just be sure to be ready to cover your ageratum if you have one of those late frosts.

USDA Zone Info for Missoula

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Missoula

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