One of the first steps you take when you are getting a good idea your gardening schedule is find your 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 getting a good idea when it's a good idea to plant pennyroyal is to refer to the USDA zone info for Dublin.

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 tells us that you can get them planted much earlier than more sensitive plants.

The earliest that you can plant pennyroyal in Dublin 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. If you wait any later than that and your pennyroyal may not have a chance to really do well. If you are starting your pennyroyal indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is March 15 in Dublin. In the coldest months of winter you should expect an average low temperature of 10°F.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Dublin and it is different every year. Since half of the time in Dublin there is a last frost after March 15 be ready to cover your pennyroyal in the event of a late frost.

USDA Zone Info for Dublin

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Dublin

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