New England Planting Zones

USDA Plant Hardiness Zone Map

• The USDA plant hardiness zone map is divided into 13 zones that are distinguished by 10-degree ranges in the average annual extreme minimum temperature. These planting zones are the standard zones used for determining where a plant will grow. For example, a plant that is hardy to USDA zone 7 may not survive in USDA zone 5 due to the colder winters.

USDA Zones 3 and 4

• The northern three New England states fall into USDA zones 3b through 4b. Much of the northern half of Maine is in zone 3b, as well as most of the northern tip of New Hampshire and scattered areas in northern Vermont. Zone 3b's average annual extreme minimum temperature falls between minus 35 and minus 30 Fahrenheit. Zone 4 covers quite a bit of the three northern New England states. The top two-thirds of Maine that don't fall into USDA zone 3 fall into USDA zone 4. Cities include Greenville, Houlton and Caribou. The top one-third of New Hampshire, including Littleton and Berlin, and the top half of Vermont, including Chelsea and Montpelier, also fall into USDA zone 4. The average annual extreme minimum temperatures for USDA zones 4a and 4b fall between minus 30 and minus 20 F.

USDA Zones 5, 6 and 7

• USDA zone 5 covers the lower third of Maine, except for a few small coastal pockets that fall into USDA zone 6. Cities include Bangor, Augusta, Portland and Bar Harbor. New Hampshire cities that fall within USDA zone 5 include Newport, Concord, Peterborough and Nashua; while Vermont cities include Brattleboro, Springfield and Rutland. The southern three New England States -- Massachusetts, Rhode Island and Connecticut -- don't fall below USDA zone 5. Most of Massachusetts, including everything east of Worcester and southeast of Springfield, falls between USDA zones 6 and 7; the northwest corner of Connecticut, including Litchfield and Canaan, is in USDA zone 5b, while the rest of the state falls between USDA zones 6 through 7a. Rhode Island, on the other hand, is almost completely within USDA zone 6 except for some coastal areas which fall in USDA zone 7a. Parts of southeast Massachusetts are in USDA zone 7b.

Sunset Climate Zones

• Another zoning system that is gaining ground among the nursery trade is the Sunset climate zone map. Sunset climate zones differ from USDA plant hardiness zones in that they're based on many climatic factors including coastal influences, elevation, mountains and valleys and latitude. New England falls into Sunset climate zones 34, 37, 38 and 44. Most of these areas have a planting season that lasts between May and October, although there are some variances.