ZONE 34. Lowlands and Coast from Gettysburg to North of Boston
Growing season: late April to late Oct. Ample rainfall and humid summers are the norm. Winters are variable–typically fairly mild (around 20 degrees F/-7 degrees C), but with lows down to -3 degrees to -22 degrees F/-19 degrees to -30 degrees C if arctic air swoops in.
ZONE 37. Hudson Valley and Appalachian Plateau
Growing season: May to mid-Oct., with rainfall throughout. Lower in elevation than neighboring Zone 42, with warmer winters: lows are 0 degrees to -5 degrees F/-18 degrees to -21 degrees C, unless arctic air moves in. Summer is warm to hot, humid.
ZONE 38. New England Interior and Lowland Maine
Growing season: May to early Oct. Summers feature reliable rainfall and lack oppressive humidity of lower-elevation, more southerly areas. Winter lows dip to -10 degrees to -20 degrees F/-23 degrees to -29 degrees C , with periodic colder temperatures due to influxes of arctic air.
ZONE 39. Shoreline Regions of the Great Lakes
Growing season: early May to early Oct. Springs and summers are cooler here, autumns milder than in areas farther from the lakes. Southeast lakeshores get the heaviest snowfalls. Lows reach 0 degrees to -10 degrees F/-18 degrees to -23 degrees C.
ZONE 40. Inland Plains of Lake Erie and Lake Ontario
Growing season: mid-May to mid-Sept., with rainy, warm, variably humid weather. The lakes help moderate winter lows; temperatures typically range from -10 degrees to -20 degrees F/-23 degrees to -29 degrees C, with occasional colder readings when arctic fronts rush through.
ZONE 42. Interior Pennsylvania and New York; St. Lawrence Valley
Growing season: late May to late Sept. This zone's elevation gives it colder winters than surrounding zones: lows range from -20 degrees to -40 degrees F/-29 degrees to -40 degrees C, with the colder readings coming in zone's Canadian portion. Summers are humid, rainy.
ZONE 43. Upper Mississippi Valley, Upper Michigan, Southern Ontario and Quebec
Growing season: late May to mid-Sept. The climate is humid from spring through early fall; summer rains are usually dependable. Arctic air dominates in winter, with lows typically from -20 degrees to -30 degrees F/-29 degrees to -34 degrees C.
ZONE 44. Mountains of New England and Southeastern Quebec
Growing season: June to mid-Sept. Latitude and elevation give fairly cool, rainy summers, cold winters with lows of -20 degrees to -40 degrees F/-29 degrees to -40 degrees C. Choose short-season, low heat-requirement annuals and vegetables.
ZONE 45. Northern Parts of Minnesota and Wisconsin, Eastern Manitoba through Interior Quebec
Growing season: mid-June through Aug., with rain throughout; rainfall (and humidity) are least in zone's western part, greatest in eastern reaches. Winters are frigid (-30 degrees to -40 degrees F/-34 degrees to -40 degrees C), with snow cover, deeply frozen soil.