Kentucky's long, warm summers and mild winters make it ideal for bluegrass and horse farms. Kentucky’s planting zones have long growing seasons ideal for several different crops.
Most of Kentucky is in U.S. Department of Agriculture Plant Hardiness Map zone 6a, which indicates annual average lows of between minus 10 and minus 5 Fahrenheit. The southwestern edge to Bowling Green and a section of the southeast including Pikeville is in USDA plant hardiness zone 6b, with annual lows of between zero and 5 below zero. Two small patches on either side of Lexington are in the slightly colder zone 5b, with lows of minus 15 to minus 10.
Planting zones not only tell gardeners what the annual lows are, but also what plants will thrive in the conditions. Almost every plant has a USDA Hardiness Rating, and selecting plants in the correct range will ensure that they will weather the near-freezing winter temperatures.
Planting zones also dictate when gardeners should plant vegetables for maximum yield. Because the warm weather comes early, Kentucky gardeners can plant crops such as mustard, kale, broccoli and collard greens as early as March. For some vegetables, such as lettuce, cauliflower, radishes and spinach, there’s enough time in the long growing season for two crops.