Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Portsmouth you can figure out when you can plant iceberg lettuce by reviewing the USDA zone info.

Planting Calendar for Iceberg lettuce

Frost tolerance for iceberg lettuce:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Iceberg lettuce do ok in mild cold which tells us that you can plant them just a tiny bit earlier in the year than more sensitive plants.

The earliest that you can plant iceberg lettuce in Portsmouth is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant iceberg lettuce and expect a good harvest is probably August. If you wait any later than that and your iceberg lettuce may not have a chance to grow to maturity. If you are starting your iceberg lettuce indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Portsmouth and it will vary from year to year. Half of the time in Portsmouth it frosts late in the year after April 15 so be sure to be ready to protect your iceberg lettuce in the event of one of those late frosts.

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.