Don’t double up on sod

December 20, 2012 -  By

Turfgrass sod experts agree: Installing sod on an existing lawn will create more work in the end.

The Internet can be a tremendous tool, especially when it comes to seeking helpful information. Unfortunately, misinformation is abundant.



Consider this “advice” one website’s contributing writer offered.

“Professional landscapers often apply sod directly over grass. The sod compresses the grass and limits its exposure to sunlight and water. This quickly kills the already existing grass, in much the same way that a brick left on a lawn kills the grass beneath it. When the grass dies, it gives off nutrients that actually benefit the new sod above it. The main nutrient that the dead grass layer provides is nitrogen. Applying sod directly over grass is advantageous because it requires less work. The lawn does not need to be treated with herbicide. Also, you do not need to till your yard.”

Landscape contractors, take note: Turfgrass producers agree laying sod over an existing lawn isn’t acceptable.

“Not a good idea,” says Bob Weerts of Blue Valley Sod Farm in Winnebago, Minn., who recently dealt firsthand with a landscape consultant who had just completed an inspection for one of his customers, a national restaurant chain. The problem? A dying new lawn. The reason? The contractor laid new turfgrass sod over the existing turf weeks earlier. The new grass never rooted.

“This is not a practice that I have ever heard of working,” says Mike Blair of Green Velvet Sod Farms in Bellbrook, Ohio. In addition to the new sod’s roots drying out and dying, the decomposing turf could develop an acid or slim, causing further problems, he says.



Warren Bell of Biograss Sod Farm in Sandy, Utah, concurs it’s not wise. “The surface of the old lawn has a lot of organic matter and likely will not match the soil profile of the sod being installed,” he says. “Water will never move through the profile efficiently.”

So, if a client or employee suggests you lay new sod directly on top of an existing lawn, don’t do it.

Sod-laying tips
Here are a few pointers from Linda Bradley of Turf Mountain Sod in Hendersonville, N.C.

  • All sod must make soil to root contact. Existing turf must be extremely sparse or topped with soil before laying the new sod. Roots won’t penetrate hard ground; till or loosen the top 2 in. to 3 in. of soil.
  • Grade is important. There cannot be any water-holding spots, and water never should flow toward the building or home.
  • Weeds can grow through the new sod, so it’s important to eradicate them before installation.


This article is tagged with and posted in December 2012, Mowing+Maintenance

About the Author:

Novak is public relations manager for Turfgrass Producers International.

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