When To Dethatch a Lawn
The process of dethatching is hard on turf, so the ideal time to tackle this chore is right before grass enters its period of strongest growth. Because warm- and cool-season grasses grow most vigorously at different times during the year, the ideal time for dethatching also varies. It’s vital to know what kind of grass comprises your lawn before you dethatch.
In regions that experience frost and snow, dethatch warm-season grasses in late spring to early summer – well before heat arrives and the lawn’s water needs are high. In the warmest regions, including the Coastal South and Southern California, dethatch warm-season grass in early spring, but be sure to wait until grass is actively growing. This means you should have mowed it once or twice.
Warm-season turf types:
- Bahia grass
- Buffalo grass (doesn’t usually develop thatch)
- Centipede grass
- St. Augustinegrass
Dethatch cool-season turf types in early spring or early fall. Timing is critical in both cases. In early spring, dethatch after grass is actively growing – after you have mowed it once or twice. Time early fall dethatching to allow grass plenty of time to grow and re-establish before frost arrives.
Cool-season turf types:
- Creeping bentgrass
- Fescue (chewings, hard, red; tall fescue rarely needs dethatching)
- Kentucky bluegrass
- Rough bluegrass
- Ryegrass (perennial that rarely needs dethatching)
- Dethatch when soil is moist, not dry. If soil is too wet, dethatching may yank turf out by the roots, creating large bare spots.
- It’s best to dethatch during cooler weather.
- Mow the lawn to half its normal height right before dethatching.
- Postpone dethatching – even if it’s needed – during times of drought, watering restrictions or intense heat waves.
- Avoid heavy dethatching in mid- to late fall for any kind of lawn. Late-season dethatching sends grass into winter weak and damaged, which can affect survival.