One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The best time to plant penstemon in Portsmouth should be estimated by referring to the USDA zone info.

Planting Calendar for Penstemon

Frost tolerance for penstemon:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Penstemon can survive in moderate cold which means that you can plant them a little earlier in the year than more sensitive plants.

The earliest that you can plant penstemon 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 penstemon and expect a good harvest is probably September. If you wait any later than that and your penstemon may not have a chance to really do well. You can get started a little bit earlier by starting your penstemon indoors.

Last Frost Date

On average the last frost is on April 15 in Portsmouth. It might get as low as -5°F during the coldest months of winter.

It's important to remember that USDA zone info for Portsmouth is an average and the actual date of last frost changes from year to year. Half of the time in Portsmouth last frost occurs after April 15 so make sure that you are ready to protect your penstemon if you have one of those late frosts.

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.