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.

By referring to the USDA zone info for Ames it's a good idea to figure out when it's a good idea to plant pennyroyal.

Planting Calendar for Pennyroyal

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

Pennyroyal can survive in cold weather which tells us that you can plant them quite a bit earlier in the year than more sensitive plants.

The earliest that you can plant pennyroyal in Ames 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. Any later than that and your pennyroyal may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your pennyroyal indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Ames. You can expect an average low temperature of -20°F in the coldest months of winter.

Since the USDA zone info for Ames is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Ames you get a frost after April 15 so be sure to be ready to cover your pennyroyal in the event of a late frost.

USDA Zone Info for Ames

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Ames

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