Thatch Control in Warm-Season Lawns


Ornamental plants need to be cleaned up periodically as leaves and blooms die back.
The same is true for grass. As grass plants grow, older plant material falls away to the
soil level and can build up. This is called thatch and it can become problematic if it is
thicker than ½ inch.

A thick layer of thatch can restrict water infiltration and reduce the efficacy of
pesticide/herbicide treatments. When thatch accumulates, grass plants tend to root into this layer instead of deeper into the soil.

Since thatch dries quickly, the lawn will suffer from drought stress. Kentucky bluegrass,
zoysiagrass, bermudagrass and creeping bentgrass are the varieties of turf most likely
to be affected by thatch buildup.

Power-raking and core-aerating are the best strategies for preventing thatch buildup.
For warm-season grasses, it is best to do this in June or July when the lawn is actively
growing and can recover from thinning more efficiently. If the thatch is ½ to ¾-inches
thick, core aerating can be done. Repeat passes with the aerator until the holes are
about 2-inches apart.

If thatch is thicker than ¾-inches, it will need to be power-raked. Set the blades of the
rake only deep enough to remove the thatch so the lawn is not severely damaged.
Thatch can be prevented by fertilizing properly and avoiding excessive nitrogen
applications. Water to the root zone and only as needed. Mow at the recommended


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