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Photo Credit: ©2000 Dolezal Publishing/David Goldberg

A little bit of thatch (like here) is a good thing. To determine if your lawn has a thatch problem, get down on your knees and inspect the turf carefully. If you can see soil between the blades as you spread them with your fingers, you have normal thatch and no treatment is necessary.

If you’ve got an older lawn, chances are you’ve also got some thatch buildup. The fact is that older lawns – particularly those that received quick-greening fertilizers that spur top growth without providing much root support – are likely to have a thatch issue.

What is thatch? It’s the dead, dry remains of turfgrass roots, stolons and rhizomes that don’t decompose as quickly or easily as they should. Spotting thatch is easy: Take a walk across your lawn. Does it feel springy? If so, you have some thatch. Does it feel very springy, and do your feet sink deeply into the lawn? Then you’ve got a lot of thatch. Now get down on your hands and knees and inspect the lawn closely. You should be able to see soil between the blades. If you find fibrous yellow straw-like material, then yes, you’ve got thatch.

Now, some thatch is normal because it helps prevent water runoff, insulates the soil from too much heat, and even denies pests access to roots and stems. If you do see thatch in your lawn, grab a metal ruler or tape measure and stick it into the turf until it hits soil, then note the depth of the thatch layer. Generally, a thatch thickness of less than ¼ an inch is acceptable. If it’s between ¼-½ of an inch, you’re on your way to a thatch problem. If it’s more than half an inch thick, the problem has already arrived and requires immediate treatment.

Too much thatch is an indicator of a general breakdown in the normal decomposition process essential to growing healthy turfgrass. In rich soil with normal biologic processes, thatch is broken down fairly quickly by microorganisms and, most importantly, earthworms – which munch it up and reduce it to precious humus.

Ironically, many of the commercial fertilizers, fungicides and pesticides that get added to our lawns drive up the soil’s acidity and send earthworms and other microbes packing. Without them and their help, thatch doesn’t break down. This dynamic can be reversed by aerating your lawn, “sweetening” the soil to a 6.5-7.0 pH range and topcoating it with rich organic matter like peat moss. Of course you can only use this remedy after you’ve dethatched your lawn.