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.

By reviewing the USDA zone info for Portsmouth you should be able to figure out when it's the best time to plant polygonums.

Planting Calendar for Polygonums

Frost tolerance for polygonums:	Not tolerant of frost.
When to plant:	After the last frost has passed.

It's probably a bad idea to plant polygonums until after all chance of frost has passed because they require warm weather.

The earliest that you can plant polygonums in Portsmouth is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant polygonums and expect a good harvest is probably August. You probably don't want to wait any later than that or else your polygonums may not have a chance to grow to maturity. You can get started a little bit earlier by starting your polygonums indoors.

Last Frost Date

The average date of last frost is March 15 in Portsmouth. You can expect an average low temperature of 10°F in the coldest months of winter.

It's important to remember that USDA zone info for Portsmouth may not be accurate from year to year and the actual date of last frost changes from year to year. Since half of the time in Portsmouth there is a last frost after March 15 be ready to cover your polygonums if you have one of those late frosts.

USDA Zone Info for Portsmouth

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 Portsmouth

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