The best time to dethatch a lawn depends on the type of grass:

• For cool-season grasses (such as Kentucky bluegrass, fescues, perennial ryegrass), dethatching is best done in late summer or early fall when the grass is actively growing and can recover quickly; early spring is also a good time. This timing ensures the lawn can heal before winter dormancy or heat stress.

• For warm-season grasses (such as Bermudagrass, Zoysia grass), dethatch after spring green-up during early summer's peak growth period. Avoid dethatching when the lawn is dormant or stressed to prevent damage.

Additional tips:

• Check your lawn’s thatch layer before dethatching. If it measures 1/2 inch or more, dethatching is likely needed.

• Avoid dethatching in winter (dormant grass) or peak summer heat, as these conditions delay recovery.

• Dethatching is stressful to grass, so performing it during peak growth times maximizes recovery chances.

In summary, dethatch cool-season lawns in late summer or early fall, and warm- season lawns in late spring to early summer, always coordinating with active grass growth for best results.