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.

You can estimate when it's possible to plant pennyroyal in Houston by checking out 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 quite a bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant pennyroyal in Houston is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant pennyroyal and expect a good harvest is probably October. You probably don't want to wait any later than that or else 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 the last frost is on February 15 in Houston. In the coldest months of winter you can expect an average low temperature of 20°F.

Since the USDA zone info for Houston is an average the actual date of last frost will vary from year to year. Since half of the time in Houston you get surprised by a frost after February 15 be ready to protect your pennyroyal in the event of a surprise late frost.

USDA Zone Info for Houston

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°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 25°F.

Plants to Grow in Houston

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