Q: Do I need to dethatch my lawn each season?

A: First, what is thatch? Certain types of grasses, just like certain types of people, will grow sideways as well as upward. This is a more natural function with these grasses however, and does not at all relate to the relative amount of time spent in front of Jerry Springer with a bag of pork rinds. In fact, the sideways growth is very beneficial to your lawn’s overall appearance, as it helps to create a very thick, carpet-like yard.

Did you ever wonder why sheets of sod hold together so well? No?.... Well I’m going to explain anyway. Typically speaking, sod in the Northern U.S. is composed of Kentucky Bluegrass. This is because Kentucky Blue has a large number of rhizomes, which are sideways growing structures used to help the grass spread. These rhizomes grow underground, then periodically pop up and produce a new grass plant. The new grass plants then grow and complain incessantly about how the original plants just don’t understand them.

After a while, the rhizomes from neighboring plants start piling on top of one another. They first resemble a bunch of loosely woven strands. After a while though, they pile on top of each other and form a very thick, tight pile of dead, decaying, dying, and living rhizomes all packed together in a very tight mat. This is called “thatch.”

Once thatch reaches a certain thickness and tightness, problems begin occurring. You soon encounter what is known as the “sponge” effect. It is called this because the thatch behaves very much like a sponge. When you water the lawn or rain hits, the thatch resists the water initially and does not allow it to penetrate. Once the water amount gets high enough though, the thatch gets soaked, but holds the water like a sponge, not allowing it to get into the soil where the roots are. In addition, much like the aforementioned Jerry Springer, the thatch layer plays the perfect congenial host to all sorts of problematic bugs and fungus.

Interestingly enough, giving fertilizer and water to a lawn full of Kentucky Bluegrass is a lot like giving 40 or 50 million dollars to a 20 year old singer/actress/tartlet. Sure it SOUNDS like a great idea, but there could be unforeseeable negative consequences. In this case the extra growth in the lawn actually produces a problematic thatch layer over time.

So IF you have a thatch problem, THEN yes, it’s a good idea to dethatch. If you get on your hands and knees, and poke in between the grass plants with your fingers, are you able to find the soil easily? If instead you have a hard time prying apart the thick, brown straw-like net, you’ve got a potential thatch problem brewing. A dethatcher basically has blades that spin around vertically and rip up rows of the grass right down to the roots, while leaving plenty to spread back in.. The torn up stuff then needs to be raked or blown away.

One other option that has many benefits, including thatch control is core aeration. This procedure punches holes all throughout the lawn and pulls out plugs of soil, making it look as if your lawn hosted a party of Canadian Geese after a thanksgiving feast. The benefit to this is that the holes open up channels through the thatch, which allows water and nutrients to get through unhindered. If you aerate your lawn thoroughly each Fall, you will likely never have to deal with thatch as a problem.