One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can figure out when to plant pennyroyal in Ann Arbor by looking at 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 do well in a bit of cold which tells us that you can plant them much earlier in the year than other plants that might not handle the cold.

The earliest that you can plant pennyroyal in Ann Arbor 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. 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

In Ann Arbor the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -10°F.

Since the USDA zone info for Ann Arbor is not always accurate the actual date of last frost will vary from year to year. Since half of the time in Ann Arbor it frosts late in the year after April 15 be ready to cover your pennyroyal in the event of one of those late frosts.

USDA Zone Info for Ann Arbor

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Ann Arbor

You may be interested in your other planting guides for Ann Arbor.