Dethatching Your Lawn

The results of a power rake.

The results of a power rake.

Every spring we are asked by our customers if they need to power rake or dethatch their lawns. It seems like the logical thing to do, after all, we clean out our cars and basements– shouldn’t we also clean thatch out of our lawns? The answer to that question is usually “no.”

Thatch, as defined by Dr. James Beard, is “a tightly intermingled layer of dead and living stems and roots that develops between the zone of green vegetation and the soil surface.” In the most basic sense thatch is what gives the turf that “spongy” feeling when you walk on it. If you have ever walked on a recently established turf you may have noticed that it feels very firm. That is because a thatch layer has not yet developed.

Dethatching is an aggressive procedure that rips and tears the turf, resulting in only a small amount of thatch reduction. Most thatch consists of living roots and stems and is not removed by power raking.

You also may be surprised that grass clippings do not contribute to thatch accumulation. Most thatch is attached to turf plants or their root system. Grass clippings are mostly water and highly biodegradable, therefore making it best to return them to your lawn.

Instead of dethatching, aeration is recommended. Aeration removes cores of soil from the lawn. These cores break down and redistribute valuable nutrients to the soil and also topdress the soil with a thin layer of dirt which deduces thatch. The holes left in the lawn provide passageways for air, water, and nutrients. As the soil and roots expand to fill the holes, the surrounding soil is allowed to loosen, reducing compaction.
Aeration is a service best performed in the summer or fall. Spring aeration can reduce the effectiveness of spring applied crabgrass control.

So, if you’re feeling ambitious, go ahead and power rake your lawn. It will probably be a good workout, but of little benefit for your lawn.

Some information and pictures provided by: Dr. Kevin Frank, Michigan State University