Turf Care 101:Dethatch

What is Thatch?

Thatch is a communion of dead grass, roots and other matter that builds up in grass over time.  It’s very common and collects on most lawns at some time or another.  Thatch collects above the soil at surface level and becomes intertwined in grass stems.  When the cycle of decomposition is delayed for any variety of reasons, dead matter will begin to build up.  As the build up increases the matter becomes stacked and then packs down or mattes, causing healthy grass blades to become stressed and weaken.

Dethatching Benefits

Left untreated, thatch can literally choke a lawn to death. As thatch thickens it robs the soil of air and hinders water absorption and nutrient penetration to the soil and root system. Not only will excessive thatch kill the grass, left undeterred long enough it will damage the soil so that even if removed, new growth in that area will be sparse at best without soil treatment. Thick thatch levels can also become a haven for insects. Moisture rich matted thatch can be an excellent breeding ground for mosquitos and disease. Knowing the level of thatch you have will assist you in the best way to combat the problem properly.

Dethatching Frequency

Dethatching can be performed any time during the year outside of drought or frost. Don’t wait for the fall to perform a dethatching treatment at a moderate or excessive level of thatch unless you are in a prolonged season of drought.

After Dethatching

Most people are shocked to see how much thatch even a healthy lawn can collect in a single growing season. Lifting the thatch to the surface is just the first step. After the lawn is dethatched, the thatch must be removed from the top of the grass or it will mat back down to the soil surface. You can use a hand rake or blower to pile the thatch for bagging or you can use a lawn/leaf vacuum for quick clearing.

Annual maintenance dethatching (thinning thatch a ¼ inch in depth or less performed with a spring tine blade dethatcher) should leave no noticeable damage to the lawn. Actually it is likely that you will find that your grass has greened up a little over the next week or so due to increased exposure to air and water.

Moderate thatch dethatching may expose thinning areas and bald spots caused by soil compaction. An overseeding treatment followed by fertilizer will spruce these areas up in 2-3 weeks if performed in season. If performed late in the fall, you should notice a much thicker lawn will grow in the spring.

Excessive thatch treatment is more intrusive to the lawn and the soil. After a dethatching and aeration treatment, you may notice bald spots and core holes in the soil. These holes are needed to help the soil and existing grass root system strengthen and recover, however you should wait at least 7 – 10 days before an overseeding treatment to allow the soil some time to recover.

Thatch creates a water barrier, prevents new grass from growing and harbors insects. It collects quickly and before long the lawn and its entire root system is at risk. Lawn dethatching, when performed as needed, will go a long way in maintaining a healthy, green lawn.