Here are the basics to help you buy the best grass for your yard. Blends and mixtures improve a lawn's appearance. A seed blend contains several varieties of the same kind of grass, such as three types of Kentucky bluegrass. A blend usually gives a lawn a more uniform look. A seed mixture combines several kinds of grasses for example, Kentucky bluegrass, tall fescue, and perennial ryegrass. Such a combination promotes a green lawn all season. Cool-season grasses grow best in northern lawns. The grasses grow vigorously in spring and fall but may go dormant and turn brown in the heat of summer. Cool-season grasses commonly come in blends or mixtures. Warm-season grasses are adapted to growing conditions in the South. They grow well in hot weather but go dormant in cool weather. Before buying grass seed, call your cooperative extension service. Experts there can recommend the best type of grass for your locale and situation.