What is thatch?
Thatch is the layer of living and dead stems, roots, stolons, and rhizomes between the green blades
grass and the soil surface. A thin layer of thatch (less than 1/2 inch thick) can be beneficial to
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
causing reduced root growth and increased potential for drought stress.
When to dethatch:
If your lawn has a bouncy feel to it when you walk on it, thatch is probably building up. As a
rule, plan to dethatch your lawn when the thickness of the thatch is more than 1/2 inch deep. To
determine the thickness, remove a small square of your lawn to a depth of about 3 inches and measure
brown layer between the grass blades and the soil surface. For both cool and warm-season grasses,
best time to dethatch is mid-to-late spring or early fall. During this time when the turf is
growing, the grass will quickly recover from injury.
The frequency of thatch removal depends upon how fast the thatch layer builds. Lawns that are
overwatered, over fertilized, or growing on heavy clay soils may accumulate thatch quickly. Turf
species is also a factor. Grasses such as bermudagrass, bentgrass, and Kentucky bluegrass build a
thatch layer over several months and may need to be dethatched yearly. Grasses such as tall fescue
perennial ryegrass do not produce much thatch and may not need to be dethatched more than every few