One of the best tools that you have as gardeners to help us estimate 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.

It's a good idea to determine when it's a good idea to plant scarlet runner beans by referring to the USDA zone info for Portsmouth.

Planting Calendar for Scarlet Runner Beans

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

Since scarlet runner beans are not cold tolerant it's necessary to wait until after the last frost before you can plant them.

The earliest that you can plant scarlet runner beans 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 scarlet runner beans and expect a good harvest is probably August. If you wait any later than that and your scarlet runner beans may not have a chance to really do well. Starting your scarlet runner beans indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on March 15 in Portsmouth. It might get as low as 10°F during the coldest months of winter.

Since the USDA zone info for Portsmouth is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Portsmouth you get surprised by a frost after March 15 so be sure to be ready to cover your scarlet runner beans in the event of a surprise late frost.

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.