Management of cool-season turfgrasses in the fall is mainly directed toward fertilization, broadleaf weed control and mowing. Fertilizer and weed control recommendations are made with great authority because of a good research base. Fall mowing height has not received as much attention, especially since mowing is often considered a curse by the end of along growing season. In the summer, Kentucky bluegrass and tall fescue turf is mowed high (3-4 inches) to insulate the sward against moisture and temperature stress and to prevent germination of light-sensitive seed of crabgrass and other warm-season annuals. In the fall, however, the mowing height should be lowered progressively. To understand the importance of mowing height one needs a basic knowledge of the growth of vegetative turfgrasses.
Dougherty, C. T. and Powell, A. J. Jr., "Principle of Fall Turf Management" (1988). Agronomy Notes. 64.