Summer stress aside, diverse kinds of grasses naturally vary in visible appearance, including height, growth habit, leaf color and thickness, and development of flowers and seedheads. Common Wisconsin lawn grasses are cool-season, including Kentucky bluegrass, perennial ryegrass, and fine fescues. Within a lawn you may often notice variations in color among these cool-season grasses in summer. Conversely, warm-season grasses find temperatures in the 80 degree range ideal and can produce food very efficiently. As warm-season grasses, these species flourish in the heat, outcompeting cool-season lawn grasses and overgrowing vegetable and flower plantings.