One of the first steps you take when you are estimating 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.

In Walla Walla you can figure out when it's a good idea to plant pennyroyal by reviewing 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 more sensitive plants.

The earliest that you can plant pennyroyal in Walla Walla 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 really do well. You can get started a couple of weeks earlier by starting your pennyroyal indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Walla Walla. It might get as low as 0°F during the coldest months of winter.

Since the USDA zone info for Walla Walla is just an average the actual date of last frost is different every year. Since half of the time in Walla Walla last frost occurs after April 15 be ready to cover your pennyroyal in the event of a late frost.

USDA Zone Info for Walla Walla

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Walla Walla

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