One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

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

Planting Calendar for Pennyroyal

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

Pennyroyal are one of those plants that can tolerate quite a bit of cold weather which tells us that you can start planting them much earlier than plants that are more sensitive to the cold.

The earliest that you can plant pennyroyal in Caledonia 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 really do well. You can get started a few weeks earlier by starting your pennyroyal indoors.

Last Frost Date

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

Keep in mind that USDA zone info for Caledonia is an average and the actual date of last frost is different every year. Half of the time in Caledonia you get surprised by a frost after April 15 so make sure that you are prepared to protect your pennyroyal in the event of a late frost.

USDA Zone Info for Caledonia

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 Caledonia

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