Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By looking at the USDA zone info for Portsmouth it's possible to determine when to plant bidens.

Planting Calendar for Bidens

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

Since bidens are not cold tolerant you need to wait until after the last frost when the weather gets warmer before you can plant them.

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. Any later than that and your bidens may not have a chance to really do well. Starting your bidens indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Portsmouth the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -5°F.

Since the USDA zone info for Portsmouth is not always accurate the actual date of last frost will vary from year to year. Since half of the time in Portsmouth there is a last frost after April 15 be ready to cover your bidens in the event of a surprise 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.