Kentucky Bluegrass is a cool season grass that is one of the best known and most common grasses. Kentucky bluegrass produces a nice, thick lawn and will spread over time to fill in bare areas. It prefers full sun, but will tolerate some shade as well. It has shallow root systems, so it does not perform well in drought or hot conditions. It can also be susceptible to weeds and diseases. To provide a more disease resistant, drought tolerant lawn, Kentucky Bluegrass is most often combined with other grass types, such as Perennial Rye Grass to form a “blend”.