Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant pennyroyal in Elk River should be figured out by using 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 cold which tells us that you can get them planted much earlier than more sensitive plants.

The earliest that you can plant pennyroyal in Elk River 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. You probably don't want to wait any later than that or else your pennyroyal may not have a chance to grow to maturity. If you are starting your pennyroyal indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Elk River the average date of last frost happens on May 15. It might get as low as -25°F during the coldest months of winter.

Since the USDA zone info for Elk River may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Elk River last frost occurs after May 15 so be sure to be ready to cover your pennyroyal if you have a surprise late frost.

USDA Zone Info for Elk River

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 Elk River

You may be interested in your other planting guides for Elk River.