What is thatch? Do you have too much?


Do you notice your lawn is spongy as you walk in it?  If you mow shorter then normal to you have brown spots?  Does your lawn take longer to green-up in the spring?  If you answered yes you probably have excess thatch that must be addressed immediately to keep your lawn from failing.

Thatch is a tight, brown, spongy, organic layer of both living and dead grass roots and stems that accumulates above the soil surface.  It is natural and good to have a 1/4 inch of thatch.  This keeps weeds from growing in the lawn and helps hold in moisture.  It is also an environment for healthy bacteria in your lawn that breaks down the thatch to produce nitrogen to feed your lawn!   Yet environmental conditions, soil conditions and management practices (irrigation, mowing, fertilization) influence the rate and amount of thatch accumulation.  Excess build-up of thatch tends to be a problem on Kentucky bluegrass, bentgrass and fine fescue lawns. It is rarely a problem with tall fescue, wheatgrass, bromegrass or buffalograss.  This means that thatch control must be an ongoing practice for your lawn.  Contrary to some thoughts, grass clippings do not contribute to thatch accumulation and should be returned to the lawn during mowing to reuse the nutrients they contain.  

You can measure your thatch layer by cutting a circle of turf and removing it, including the underlying soil.  If you have excessive thatch it will be easy to see where the thatch stops and the soil begins.  You want to have a 1/4 inch of thatch.  If it is greater than a 1/4 inch  it is best to address your build-up before it exceeds 1/2 inch in thickness. The thickness can increase quickly beyond this point, making it difficult to control later. As the thatch layer thickens, it becomes the main rooting medium for the grass. This predisposes the turf to drought stress or winter kill and increases the possibility for insect, disease and weed problems. Also, fertilizers and pesticides applied to an excessively thick thatch lawn work less effectively.

Now what?  Well your choices are power de-thatching or aeration.  There are other products such as liquid bacteria but so far we haven’t tested enough to use on clients lawns!  De-thatching can be likened to getting liposuction.  It is great and removes lots all at once.  But if you don’t eat healthier you will not feel the full effects of a fit body and will probably need lipo again.  So aeration improves the over all health of your lawn so that it can control the thatch it’s self and live healthier.  For more detailed information the articles about aeration and de-thatching.