Thatch: What it’s Good For and How to Manage it in Your Lawn

By Allyn Paul, filed under Lawn Tips.

One of the most misunderstood elements in your lawn is the thatch layer. People hear the word and immediately think of ways to eliminate it. But thatch is good for your lawn when kept at proper levels.

What does thatch do for your lawn?

The thatch layer is the collection of dead grass, roots, leaves and other organic matter residing just above the soil line amongst the grass plant’s crowns. (crowns are the base of the grass plant where the blades originate from) A proper thatch layer will be around one inch thick on average and appear “airy” and not matted or compressed.

In good conditions, the thatch layer serves several purposes that contribute to healthy turf.

  • Shades the root system: if you have no thatch at all, the the summer sun will beat down directly on the turf crowns and dry them out, as well as heat up the grass’ root system and possible burn it. A proper thatch layer creates shade for these delicate parts of the turf.
  • Aids in moisture retention: a good layer of thatch keeps moisture from evaporating so quickly so the soil can retain moisture in between waterings.
  • Reduces soil erosion: Once again, it you have no thatch at all, during heavy rains, the soil can literally wash away from around turf roots and expose them. A solid thatch layer disperses heavy flow, keeping soil levels intact.
  • Promotes microbial activity: lots of microbes and bacteria reside in the decayed thatch layer and these microbes are a part of the overall “soil food web” that is the foundation of healthy turf.

How to control thatch layer if too thick.

detail diagram of thatch layer in bluegrassIf your lawn feels extremely spongy when walking on it, you could have a thatch problem. Lawns that have been sodded many times will experience an over-abundant thatch layer during the first 4 or 5 years after installation. An out of control thatch layer will thin out the lawn and cause shallow rooting; here’s why:

Thatch layers over 1″ thick and matted will stop water and nutrients from getting down below the soil line. In addition to this, grass plants will have to compete for space and turf roots will grow shallow in order to obtain moisture. Shallow-rooted turf grass will eventually die, thus creating an even worse thatch problem. Eventually, if left unchecked, the lawn will turn to hay.

The best way to manage thatch layers in any lawn is the aerate yearly. Aeration is a process whereby cores of soil are removed and holes are punched in the thatch layer, thinning it out. The cores are deposited back onto the lawn to release soil bacteria that naturally feed on thatch as well. (BTW–those foolish aeration shoes they sell with spikes on them are worthless and will destroy your back! A true aeration will actually remove cores of soil that are about the size of dime rolls.)

If you have an extreme thatch problem of 2″ or more, you should aerate your lawn with a double pass in the Spring, and again in the Fall. An aerator can be rented for about $50 per day, but requires a truck to transport it.

Whatever you do, never power rake your lawn as this will remove 100% of the thatch and also rip out much of your good grass in the process. In my opinion, any landscape professional who offers power raking is not doing what’s best for his customers.

If you feel your thatch layer is so bad that even double aerations will not control it, then lightly rake with a metal rake prior to aerating in the spring to help loosen the matted thatch, then mow with your bagger to suck up the loosened materials.

Remember, no matter what your thatch layer thickness, you should aerate your lawn in the Spring as part of your overall organic lawn maintenance practices. It’s also a good idea to lay down a nice starter fertilizer after the aeration so the nutrients can get directly into the turf’s root system! Best of luck!

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5 Responses to “Thatch: What it’s Good For and How to Manage it in Your Lawn”

  1. Tommy Says:
    4Avatars v0.3.1 v0.3.1

    Excellent article. I’ve always been a little confused about thatch and thatching. Every spring I think I should cuz it all looks so bad and thick…but I haven’t nor aerated. But this time of the year you can practically kick all the old dead and dried grass up with your feet. Does the relative height of your grass factor? I know I keep mine way too tall (lots greener that way).


  2. Owen Says:
    4Avatars v0.3.1 v0.3.1

    You may want to check out this site. http://www.organiclawnsforamerica.com

    It is a six step organic approach to treating your lawn safely. You get the expertise of a professional lawn care service, enjoy the satisfaction of doing the job yourself and enjoy the convenience of having the products delivered directly to your door.

    It’s pretty cool!

  3. Allyn Paul Says:
    4Avatars v0.3.1 v0.3.1

    The height of your lawn cutting does not matter with thatch. Mowing tall is a good idea as long as you keep it consistent. (though you should mow a little shorter in Fall before winter)
    This time of year, as you say, it’s tough to tell what is thatch and what is dormant turf, but in another month or so, you will be able to tell.

  4. Red Thread Lawn Fungus and How to Control It | Life and Lawns Says:
    4Avatars v0.3.1 v0.3.1

    [...] way to help fight Red Thread is by keeping your lawn’s thatch layer in proper balance. Heavy thatch layers are conducive to disease development. If thatch is thick or [...]

  5. Jess Says:
    4Avatars v0.3.1 v0.3.1

    Hey just wanted to say awesome website,
    Needed to learn about thatch and now I have, cheers!

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