One of the first steps you take when you are determining your gardening schedule is find your 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.

The earliest that you can plant napa cabbage in Portsmouth should be determined by checking out the USDA zone info.

Planting Calendar for Napa cabbage

Frost tolerance for napa cabbage:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since napa cabbage do well in cold you can plant them a lot earlier in the year than more sensitive plants.

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

Last Frost Date

The average date of last frost is April 15 in Portsmouth. In the coldest months of winter you should expect an average low temperature of -10°F.

Since the USDA zone info for Portsmouth may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Portsmouth there is a last frost after April 15 so make sure that you are prepared to cover your napa cabbage in the event of a 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.