A lawn dethatcher is a gardening tool which is designed to remove thatch, a thick layer of debris which accumulates between the soil and grass blades in a lawn. An excessive buildup of thatch can have a negative impact on lawn health, causing a lawn to turn brown and scraggly. While dethatching can be accomplished by hand, using a mechanical lawn dethatcher is much faster, more efficient, and more effective. Many garden suppliers rent out dethatchers, and it is also possible to purchase one.
Thatch is a layer of grass clippings, lawn debris, and other material. In a healthy lawn, the thatch will be about as high as the width of a pinkie finger. The thatch slowly breaks down with the assistance of bacteria, ensuring that the height stays consistent, and it provides a number of protections to the lawn, preventing the burning of the grass roots and helping the lawn retain water.
In an unhealthy lawn, the layer of thatch can become quite thick. The lawn may be overfertilized, or the soil may have become compacted, making it hard for bacteria to reach the surface and break down the thatch. One quick way to help out a struggling lawn is to aerate it by poking deep holes into the soil at periodic points in the lawn, drawing the bacteria up so that they can get to work on the thatch. Sometimes, however, dethatching is required.
Lawn dethatchers are like oversized mechanical rakes. The dethatcher is run across the lawn slowly and steadily, allowing the rotating blades of the thatcher to penetrate the grass and pull up the thatch. The blade height can be adjusted, allowing the lawn dethatcher to penetrate to various depths in the lawn, and the blade spacing can also be manipulated. The alternative to a lawn dethatcher is a rake. Hand raking a large lawn can be very time-consuming and physically stressful, and many rakes are not up to the job of dislodging thick layers of thatch.
Dethatching is best done in the fall so that new grass shoots are not damaged. It is also important to leave some of the thatch behind, as denuding the lawn entirely with a lawn dethatcher will inhibit the lawn's recovery. Once the thatch has been removed from a lawn, it needs to be raked away. The lawn will usually look absolutely horrible, with straggly grass and bare patches. However, the lawn will recover quickly, especially if it is fertilized and watered after dethatching. Some gardeners also like to add grass seed to help the lawn regrow.