One of the best tools that you have as gardeners to help us determine 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.

A way of estimating when it's the best time to plant pennyroyal is to look at the USDA zone info for Berthoud.

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 earlier in the year than other frost tender plants.

The earliest that you can plant pennyroyal in Berthoud 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. You probably don't want to wait any later than that or else your pennyroyal may not have a chance to fully mature. 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

On average the last frost has passed is on April 15 in Berthoud. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Berthoud is not always accurate the actual date of last frost will vary from year to year. Half of the time in Berthoud 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 Berthoud

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 Berthoud

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