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

You can determine when it's possible to plant pennyroyal in Decorah 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 a quite a bit earlier than more sensitive plants.

The earliest that you can plant pennyroyal in Decorah 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 pennyroyal and expect a good harvest is probably August. 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

The average date of last frost is May 15 in Decorah. 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 just an average because it is based on the USDA zone info for Decorah and it can change quite a bit from year to year. Half of the time in Decorah you get a frost after May 15 so make sure that you are ready to cover your pennyroyal if you have a late frost.

USDA Zone Info for Decorah

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 Decorah

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