The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You will be able to estimate when it's a good idea to plant pennyroyal by checking out the USDA zone info for Owatonna.

Planting Calendar for Pennyroyal

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

Pennyroyal do ok in quite a bit of cold which means that you can plant them earlier in the year than other frost tender plants.

The earliest that you can plant pennyroyal in Owatonna 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. If you wait 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 Owatonna. In the coldest months of winter you can expect an average low temperature of -25°F.

Always keep in mind that USDA zone info for Owatonna is just an average and the actual date of last frost changes from year to year. Half of the time in Owatonna you get surprised by a frost after May 15 so be sure to be ready to protect your pennyroyal if you have a surprise late frost.

USDA Zone Info for Owatonna

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 Owatonna

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