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.

The first chance to plant bidens in Portsmouth should be determined by looking at the USDA zone info.

Planting Calendar for Bidens

Frost tolerance for bidens:	Not tolerant of frost.
When to plant:	After the last frost.

It's a bad idea to plant bidens until after all chance of frost has passed because they are not cold tolerant.

The earliest that you can plant bidens 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 bidens and expect a good harvest is probably August. You probably don't want to wait any later than that or else your bidens may not have a chance to really do well. Starting your bidens indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Portsmouth the average date of last frost happens on April 15. It might get as low as -10°F during the coldest months of winter.

Since the USDA zone info for Portsmouth may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in Portsmouth you get surprised by a frost after April 15 be ready to protect your bidens 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.