According to Alberta Agriculture, “Thatch is a layer of dead and living shoots, stems and roots that builds up between the green vegetation and soil surface”.
You might be surprised to learn that a thin layer of thatch (up to ½ inch) is beneficial to your lawn. Thin layers of thatch help to provide an insulating effect against fluctuations in temperature and moisture. Excess thatch however blocks out air, light, and water from reaching root zones. Thick layers of thatch lead to shallow root growth and make your lawn less drought resistant.
Dethatching is the process of removing the thatch layer from your lawn. Regular raking alone will not remove the thatch layer. A thatching rake (or convex rake) is designed for this purpose. As you pull it through the grass, it lifts and moves the thatch to the surface where it can be cleaned up and removed with a regular rake afterward.
Lawnmower rake attachments are not effective at removing thatch at normal cutting heights. When lowered to remove the thatch layer these attachments will pull out otherwise healthy grass blades and root structures. Lawnmower rake attachments are not recommended for thatch removal.
Yardsy Lawn and Landscape uses a power rake for dethatching. Our power rake mechanically removes thatch using a flail reel which slices through the turf and lifts the thatch debris to the surface.