|Thatch is the layer of living and dead stems, roots, stolons, and rhizomes
between the green blades of grass and the soil surface.
A thin layer of thatch (less than 1/2 inch thick) can be beneficial to the
lawn because it helps to limit weed germination, reduce water
evaporation, and protect from frost damage. However, thick thatch
layers can prevent water, air, and nutrients from penetrating the soil,
causing reduced root growth and increased potential for drought stress.
Thatch also favors fungal growth and can harbor insect pests.
Some turf grass species, such as tall fescue and perennial rye grass, do
not produce much thatch. Other turf grass species, such as bermuda
grass, bentgrass, zoysia grass, and Kentucky bluegrass, have creeping
growth habits and rapidly build thick thatch layers.