The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Crookston you can determine when it's a good idea to plant pennyroyal 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 one of those plants that can tolerate quite a bit of cold weather which means that you can plant them much earlier than other plants that might not handle the cold.

The earliest that you can plant pennyroyal in Crookston 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 grow to maturity. You can get started a couple of weeks earlier by starting your pennyroyal indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Crookston. In the coldest months of winter you can expect an average low temperature of -30°F.

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Crookston and it can change quite a bit from year to year. Half of the time in Crookston it frosts late in the year after May 15 so make sure that you are prepared to cover your pennyroyal in the event of a surprise late frost.

USDA Zone Info for Crookston

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Crookston

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