Can Sod be Installed on Top of Existing Grass? Why or Why Not?

When installing sod, people tend to look for ways to simplify the process. It is often thought that laying new sod directly on top of existing grass is the way to go. This seems like an easy way to cut down the preparation time, but will end up adding more time than it saves! This is because the sod cannot survive if you lay it on top of existing grass. It might look good for a couple of weeks with proper watering, but it cannot survive in these conditions! Once the sod dies, you will end up having to re-sod again and remove all of the lawn underneath as well. Essentially, sodding over existing grass makes you have to do the job twice! It’s probably a better idea not to take any shortcuts!

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Why Won’t Sod Survive on Top of Existing Grass?

In order for sod to survive, it has to be able to form a root system. In order to do this, your sod needs to have contact with the soil beneath it. If you install sod on top of your existing lawn, the existing grass forms a layer between your sod and the soil beneath. Your fresh sod will be unable to reach the soil to develop roots. Proper preparation to the soil and ground beneath the sod is crucial to the success of your lawn. For a guide on how to properly install sod, check out our full 7-step guide.

Freshly laid sod also needs proper nutrients to thrive and to grow. Existing grass makes it hard for sod to get the nutrients it needs to survive. Have you ever set a heavy, dense object (like a brick or large rock) on top of your lawn? If the object is left there for awhile the grass underneath it will decompose. Once the object is removed the grass gets a slimy, sort of wet layer on top of it. This is what happens to the grass beneath the sod. This doesn’t seem like a great growing environment and your sod will not be receiving all of the nutrients it needs.

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A Couple of Points to Consider:

Be careful when researching ‘shortcut’ ideas for your lawn. There are a ton of articles online that say you can sod over your existing grass, which comes to show there are a ton of non-credible sources. Do your research and check out blogs run by sod companies or garden centres to ensure you are getting high quality information and tips.

It is easier to put in the time and effort now as the results will be well worth it! It is easy to take shortcuts, but they can end up costing you! Don’t skip any steps, and save yourself the trouble of having to re-sod in a couple of weeks. Save time and money by doing things right, the first time!

18 Responses

  1. Len Manke says:

    If I put down 6 inch’s of Targo — can I then install sod?

    • Cameron Shimoda says:

      Hey Len,

      I’m sorry but I’m not sure what Targo is, and I’d hate to give you inaccurate info. Feel free to provide some more details in another comment and I hope I can help 🙂

  2. Lorri says:

    If you have dirt and sparse weeds will it survive?

    • Cameron Shimoda says:

      Hey Lorri, we recommend following a land preparation regimen to make your new lawn establish properly. Getting some nutritious soil mixed in, and making the grade nice and even will help immensely with your new lawn!

  3. Glenn Norris says:

    I want to kill off my Zoysia (which is infested with creeping grass’ and weeds). How long after I use Round up can I SOD?

    • Cameron Shimoda says:

      Hey Glen,

      Read the instructions on the herbicide product carefully. I wouldn’t want to make any improper recommendations here.

      Thanks and all the best!

  4. Joe says:

    I was thinking of using a weed/grass killer first on a sparsely-filled lawn, wait until the vegetation dies/browns, then roto-tilling the area before I lay the sod down. Would there be a chance this would be successful?

    • Cameron Shimoda says:

      Hey Joe,

      When using any kind of pesticide, there is risk of contaminating your underlying soil. Follow the instructions carefully for the pesticide, and be sure to water the area, or wait for a good rain once you roto-till the area to try and flush any remaining chemical before installing sod.

      Thanks for your comment!

  5. Mark Allison says:

    I’m looking to put new sod in my backyard. My old grass is pretty much all dead and I’m looking to add 3-4 inches of soil on top of the old lawn to achieve the grade I want. Can I add soil to my existing lawn, then add the sod?

    • Cameron Shimoda says:

      Hey Mark,

      You’ll have to remove the old sod before installing new! The old sod will decompose and create harmful gases and air pockets that will wreak havoc on your new sod.

      Thanks for your comment!

      • Mark Allison says:

        Thanks, that’s what I thought, but I’ve been told it’s okay. I will remove the old sod

        • Cameron Shimoda says:

          No problem Mark! Happy to help. There’s a chance your sod could be fine on top of old sod, but it’s not a recommended practice for the reasons I explained. Enjoy your new lawn!

  6. Sandy Miller says:

    One of our neighbors laid the sod right on top of the old grass. His lawn is the thickest and greenest on the street. It is the envy of the street. I don’t know how it survived or continues to survive after about a year and a half. He does very little to his yard.

    • Cameron Shimoda says:

      Wow Sandy! That’s incredible that they had such great success with an unorthodox installation method! Conditions must have been ideal for sod establishment at the time of installation. Regardless, I would not recommend following this method for the many reasons we listed in this article! Thanks for your comment and best of luck with your lawn!

  7. Max says:

    Hello,

    Well I rototilled my old “lawn” before reading this article… Since my time machine is being repaired what steps should I take to increase survival of the new sod.

    I have added some fish meal and some black earth soil on top… It’s been a week since I rototilled it.

    Thank you

    • Cameron Shimoda says:

      Hey Max, there’s a chance new lawn could be fine! We just worry about air pockets and soft rotten areas where your old lawn is decomposing. Hopefully the fishmeal and black earth helps build up the topsoil layer. Try using a roller on your new lawn after installation. That may help with your chances of success.

      All the best and enjoy your new lawn!

  8. Joe says:

    Hi there!

    I laid sod on a small sloped area next to my house. However, I didn’t know as much as I should have and I laid some pieces vertical (with the slope) vs horizontal. Will everything still be fine? Or should I change the direction of the sod while it is still fresh?

    • Cameron Shimoda says:

      Hey Joe,

      Depending on the severity of the slope, your sod could still be fine! On steep slopes, the vertical placement is key, but as long as your sod won’t shift as it settles, things should be fine. Continue to monitor it as it establishes and just be very careful on your first mow.

      All the best and enjoy your new lawn!

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