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 first opportunity to plant pennyroyal in Missoula should be determined by checking out the USDA zone info.

Planting Calendar for Pennyroyal

Frost tolerance for pennyroyal:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Pennyroyal are very cold tolerant which tells us that you can plant them much earlier than more sensitive plants.

The earliest that you can plant pennyroyal in Missoula is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant pennyroyal and expect a good harvest is probably September. Any later than that and your pennyroyal may not have a chance to fully mature. Starting your pennyroyal 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. It might get as low as -15°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Missoula is an average and the actual date of last frost changes from year to year. Since half of the time in Missoula you get surprised by a frost after April 15 be ready to cover your pennyroyal 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.