The snow has melted and it’s a tradition; dethatching your lawn. But should you be doing this to your lawn? Read on and you just might save yourself some work.
What is Lawn Thatch?
Thatch is the build up of old grass roots and rhizomes. It is not the result of leaving grass clippings on the lawn. In fact grass clippings left on the lawn will reduce the amount of thatch. As the clippings decompose they also help decompose old roots and rhizomes.
Different grasses produce thatch at different rates. Warm climate grasses such as zoysia, Bermuda and buffalo produce thatch faster and may need to be dethatched more often. Cool season grasses such as bluegrass, fescue and ryegrass produce thatch more slowly.
Some thatch is actually good for grass since it:
- keeps soil cool
- slows water loss
- insulates plant crowns from temperature fluctuation
- improves tolerance to foot traffic.
Do You Have a Thatch Problem?
Healthy grass has thatch. You only have a problem if the thatch layer gets too thick so that water and air have trouble getting to grass roots.
A thatch layer that is less than 1/2″ thick, is not a problem. Leave the grass alone.
To measure the thickness of thatch, poke around the grass until you find the brown layer near the bottom of the grass blade. With your finger or a stick, poke a hole through the brown layer to the top of the soil. Measure the thickness of the thatch.
When is the Right Time to Dethatch?
Dethatching is tough on your grass and you should time it so that the grass has sufficient time after the operation to regrow and repair the damage done by dethatching.
Warm season grasses can be dethatched in spring or fall. It is best not to do it in the middle of summer.
Cool season grasses should be done in early fall (late August or early September in zone 5) since this is the time when grass grows the best.
Dethatching in fall results in fewer weed problems.
Early Spring Dethatching in Snow Country is a Bad Idea
In the north, it has become a common ritual to dethatch as soon as the snow melts. People seem to want to get outside and do something, but dethatching at this time of year is a terrible idea. First of all, most northern grass does not need to be dethatched, in which case you are just damaging the grass plants. Secondly, the ground is still very wet in early spring. Walking on it compacts the soil, damaging soil structure, which makes it harder for your grass to grow. Stay off the lawn in spring.
What is the Best Way to Dethatch?
According to the Ohio State University power dethatchers and p0wer rakes work very well. Dethaching attachments for lawn mowers do not work. The best way to keep thatch down is to perform core aeration. Core aeration also has the benefit of improving soil structure–you solve two problems at once. In clay soil core aeration really only works in spring when the soil is moist. By fall it can be difficult to get the machines to go deep enough to get a good sized plug.
1) Thatch – The Accumulation in Lawns: http://ohioline.osu.edu/hyg-fact/4000/4008.html
2) Photo Source: The Lawn Company