One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By reviewing the USDA zone info for Portsmouth you will be able to determine when it's a good idea to plant basil.

Planting Calendar for Basil

Frost tolerance for basil:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

It's not a good idea to plant basil until after the last frost when the weather gets warmer because they are not cold tolerant.

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

Last Frost Date

The average date of last frost is April 15 in Portsmouth. 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 can change quite a bit from year to year. Half of the time in Portsmouth you get a frost after April 15 so make sure that you are ready to cover your basil in the event of 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.