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.

In Romeoville you can figure out when it's a good idea to plant pennyroyal by looking at 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.

Since pennyroyal do well in cold you can plant them much earlier in the year than more sensitive plants.

The earliest that you can plant pennyroyal in Romeoville 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 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 Romeoville. In the coldest months of winter you can expect an average low temperature of -15°F.

Always keep in mind that USDA zone info for Romeoville is just an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Romeoville you get surprised by a frost after April 15 be ready to cover your pennyroyal if you have one of those late frosts.

USDA Zone Info for Romeoville

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 Romeoville

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