The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By looking at the USDA zone info for Portsmouth you will be able to figure out when you can plant spearmint.

Planting Calendar for Spearmint

Frost tolerance for spearmint:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Spearmint do well in cold which means that you can get them planted much earlier than other frost tender plants.

The earliest that you can plant spearmint in Portsmouth 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 spearmint and expect a good harvest is probably September. Any later than that and your spearmint may not have a chance to grow to maturity. Starting your spearmint indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Portsmouth. In the coldest months of winter you can expect an average low temperature of -10°F.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Portsmouth and it changes from year to year. Half of the time in Portsmouth there is a last frost after April 15 so always be ready to cover your spearmint if you have one of those late frosts.

USDA Zone Info for Portsmouth

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°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 -5°F.

Plants to Grow in Portsmouth

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