Many older, established lawns become rough and uneven over time as the turfgrass gradually thins. Sparse, thin lawns have less foliar growth and cushioning effect than thick, dense turfgrass. Thin lawns may be caused by poor maintenance, shade, insects, diseases, and other factors. The reestablishment of a healthy, thick turf would help to alleviate this problem. Bluegrass is generally the best grass for sunny areas, while the fine leaf fescues tolerate considerable shade.
Tall fescue is also shade tolerant.
Freezing and thawing of the soil during late winter and early spring also contributes to the roughness of lawns. Small castings left on the soil surface by earthworms also contribute to the roughness of lawns. While earthworms are partially responsible for the roughness of lawns, their activity improves the growing environment of the turfgrass plants. Earthworms improve the turfgrass environment by helping to decompose thatch. Their holes improve air and water movement in the soil.