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 USDA zone info for Portsmouth can be used to figure out when to plant canna.

Planting Calendar for Canna

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

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

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. Any later than that and your canna may not have a chance to really do well. You can get started a little bit earlier by starting your canna indoors.

Last Frost Date

On average the last frost is on April 15 in Portsmouth. In the coldest months of winter you can expect an average low temperature of -5°F.

Keep in mind that USDA zone info for Portsmouth is an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Portsmouth it frosts late in the year after April 15 so be sure to be ready to cover your canna if you have a late frost.

USDA Zone Info for Portsmouth

Here is the info for USDA Zone 6b.

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

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

Plants to Grow in Portsmouth

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