Before planting it is a good idea to find your USDA Zone info to estimate 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 Missoula should be read to estimate when to plant flower-of-an-hour.

Planting Calendar for Flower-of-an-Hour

Frost tolerance for flower-of-an-hour:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Flower-of-an-Hour do ok in very little cold which tells us that you can plant them a bit earlier in the year than more sensitive plants.

The earliest that you can plant flower-of-an-hour in Missoula is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant flower-of-an-hour and expect a good harvest is probably August. Any later than that and your flower-of-an-hour may not have a chance to fully mature. Starting your flower-of-an-hour indoors is a great way to get them started a few weeks earlier.

Last Frost Date

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

Always keep in mind 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 always be ready to cover your flower-of-an-hour in the event of 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.