Mixtures and Blends
Cool-season grasses are frequently packaged in either a mixture or a blend. Mixtures have two or more species of grass, and blends contain two or more cultivars of the same species. There are many advantages to planting a mixture or blend. For one thing, the turf will be more resistant to diseases and pests, because each cultivar or species has its own strengths and weaknesses. And since most lawns have a variety of growing conditions, the different grasses can grow where they are best adapted within your lawn.

In a typical mixture containing bluegrass, ryegrass, and fine fescue, the fescues will thrive in the shady portion of the lawn, while the bluegrass will do best in the sunny areas. If conditions should turn adverse for one of the grasses, you won't lose the entire lawn, just the part that's made up of the susceptible grass.

Unlike cool-season grasses, warm-season ones tend to be planted as monostands, meaning that a single type of seed is planted, not a mixture. Their growth via stolons and rhizomes makes them so vigorous that other grasses cannot compete. Because of their distinctive appearance, some grasses, such as the original tall fescues and most native grasses, also look better planted alone.