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.

The first opportunity to plant canna in Portsmouth should be estimated by using the USDA zone info.

Planting Calendar for Canna

Frost tolerance for canna:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Canna are not cold tolerant which means that you need to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant canna 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 canna and expect a good harvest is probably August. You probably don't want to wait any later than that or else your canna may not have a chance to fully mature. If you are starting your canna indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Portsmouth. You can expect an average low temperature of -10°F in the coldest months of winter.

Just be sure to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Portsmouth and it will vary from year to year. Since half of the time in Portsmouth it frosts late in the year after April 15 be ready to cover your canna if you have a surprise late frost.

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.