The Great Lakes

ZONE 35. Ouachita Mountains, Northern Oklahoma and Arkansas, Southern Kansas to North-Central Kentucky and Southern Ohio
Growing season: late April to late Oct. Rain comes in all seasons. Summers can be truly hot and humid. Without arctic fronts, winter lows are around 18 degrees F/-8 degrees C; with them, the coldest weather may bring lows of -20 degrees F/-29 degrees C.

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 41. Northeast Kansas and Southeast Nebraska to Northern Illinois and Indiana, Southeast Wisconsin, Michigan, Northern Ohio
Growing season: early May to early Oct. Winter brings average lows of -11 degrees to -20 degrees F/-23 degrees to -29 degrees C. Summers in this zone are hotter and longer west of the Mississippi, cooler and shorter nearer the Great Lakes; summer rainfall increases in the same west-to-east direction.

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 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.