"> How to prevent nutgrass from growing through your above ground pool liner – Above Ground Pools Know it All

How to prevent nutgrass from growing through your above ground pool liner

If you have found this article, you have either experienced having some grass grow through your above ground swimming pool’s liner, or you are planning on getting an above ground pool and heard that grass can grow in it.

To verify this, grass can grow through a pool liner. For 35 years, I have seen it and learned how to prevent it from happening.

With the exception of a concrete floor, there is no guarantee that nutgrass or nutsedge won’t grow through an above ground pool liner. You can greatly lessen the chance of it growing by removing all of the sod’s root mass, using a granular nutgrass killer, and then installing a liner guard just before installing the pool’s liner.


It’s common for people to think that anything can grow through a liner. This is not true, but there is one type of grass that will absolutely grow through your pool liner just like it’s not even there. And that is nutgrass or nutsedge. Out of the few naturally occurring things that can make a hole in a liner, nutgrass is the most common.

Plants need sunlight to grow. This is why nothing grows through pool liners and how weed blocks work. Even if you put a pool up directly on the grass, the grass will die because it cannot get any sunlight through the liner.

Nutgrass is a different story. Nutgrass can lie dormant and then decide to grow straight up forming a needle-like blade. This needle blade will poke through most things and easily pierce a vinyl liner on the way to finding sunlight.


Nutgrass or nutsage growing through asphalt in a parking lot

Over the decades of me working with above ground swimming pools, I’ve come across some non-believers about just how able nutgrass is at growing through things. They believe that a simple week barrier or plastic sheeting(visqueen) will do the trick and that I’m just trying to sell them something.

“Have you ever seen grass growing through black asphalt on the side of a road or in a parking lot?”, I always ask. “Well, that’s nutgrass. And if it can grow through asphalt, what do you think a little layer of plastic can do to stop it”? If they have ever noticed grass growing through a blacktop, then they get it and take my advice after that.


Usually, when the subject of nutgrass comes up, I get two reactions. The first is the guy who says “I don’t have to worry about that. My yard doesn’t have nutgrass”. Now, I’m a big believer in the power of positive thinking, but having a high level of surety about not having nutgrass in your yard won’t keep you from having it.

The second response I get is the question “How do I know if I have nutgrass”?

My answer is always “You don’t”. There are two things about nutgrass that make it hard to tell if it’s there. One is that it looks like normal grass and blends in well with different types of grasses. The other is that it can be lying dormant, and if so, there will be no sign of it except the little round nut it has attached to it.

Sometimes I can find and see nutgrass while digging for the pool installation. Other times I can clearly see it when someone removes the grass prior to me getting there for the install and some blades of it have grown up in the open cleared area of the yard.

nutgrass shown with the nuts attached on a top rail of an above ground pool

The only way that I know how to identify it is by gently digging up a single green blade of grass and finding that it has a small round brown nut attached to it by a sturdy string-like root. That’s it.

There is no other way for me to identify it, so I can never say that a yard definitely doesn’t have it. It can occasionally flower, and when it does, you may be able to identify it. I wouldn’t rely on that though unless you are someone who works with grasses and has an eye for it. And if you are one of those people, then you know more than I about it.


When I started installing above ground swimming pools in the eighties, the understanding was that nutgrass only grew in the southeast US states. Over the decades though, nutgrass migrated north and now grows in almost all areas of the US.


When liner pads first came out, retailers and manufacturers were giving guarantees that using a liner pad will stop nutgrass from growing through a pool liner. They found out quickly that wasn’t true, so they stopped.

Occasionally, I’ll come across a retailer who will say a liner pad prevents nutgrass damage. If you see this, it will tell you one or two things about the retailer. They either don’t know what they are talking about or don’t care and are trying to sell you something no matter what. Either one should give you pause in buying from them.


As I stated earlier, only a concrete floor will guarantee no nutgrass damage to 100 percent. Concrete is expensive though and not really worth the hassle and expense for almost everyone getting an above ground pool.

There are some things you can do though that work really, really well at preventing nutgrass from growing under your pool.

1 When preparing the ground for installation, remove all of the root mass associated with the grass

Even with the less expensive Intex/Coleman soft-sided above grounds, all the grass should be removed before installing on the earth. Probably the most common mistake people make with installing soft-sided pools is that they don’t remove the grass and just try to level the earth by adding sand over the grass.

You want to remove all the grass AND all the root mass (sod) along with it before leveling and installing the pool.

Many years ago, I only had a sod cutter to remove the sod for my above ground pool installations. And even though sod cutters work very well, I eventually graduated to using a small skid-steer (Bobcat type) machine. A sod cutter is adjustable and can remove up to four inches deep of sod. This is usually deep enough to get most of the root mass associated with the grass.

When I stopped using a sod cutter and replaced it with a skid-steer machine, I started taking out more than the four inches of sod mass that a sod cutter could remove. This has a minor negative in that there is more earth to deal with as I am taking out more, and the pool will sit in the ground a little lower. But I noticed something after a while of doing this.

I noticed that since I had been using my machine to remove the sod, there were much fewer occurrences of nutgrass growing in the pools I installed. I eventually deduced that this was because I was taking out more of the root mass (more than 4” deep) of the sod.

Most if not all of the nutgrass is in the sod. Removing all of it will greatly reduce the chance of having nutgrass grow through your future pool.

2 Purchase and properly apply a granular nutgrass killer

SedgeStop nutgrass killer used to prevent nutgrass from growing in a above ground swimming pool
This product was purchased at an Ace Hardware store

As a pool installer, I buy 50-pound bags of the granular chemical that kills nutgrass. A couple of times over recent years, I have run out of killer and was forced to go to a Home Depot or Lowes to get whatever they carry that kills nutgrass.

What these stores carry is this liquid nutgrass killer made by Image. Now, I’m not saying that this product is not good. What I am saying though is that I have applied this liquid product and it didn’t do a good job at preventing nutgrass from growing through pool liners.

Since nutgrass can lie dormant for a while, it’s best to use the granular type of killer for preventing it with pool liners. This is because the chemical is a “preemergent”, which means it is designed to kill the plant right when it starts to grow.

Applying enough granular nutgrass killer with a spreader will evenly distribute the chemical over the entire pool bottom. You’ll want to apply this directly to the earth before the liner and/or liner guard goes down so it can make a nice top layer of poison.

NOTE: I have seen instructions that say to rake and work this nutgrass killer into the earth. I strongly disagree with this instruction. I instead believe that an even layer of the preemergent is best at preventing nutgrass from growing through a pool liner.

3 Purchase and lay down a liner guard/pad

By themselves(without nutgrass killer), a liner guard or pad will only marginally prevent some nutgrass from making it through the pool’s liner on it’s way to sunlight.

But if you use one in addition to having a good layer of nutgrass killer just beneath it, then it works pretty well. My feeling is that the liner pad helps create a better “death zone” for the chemical killer to work. The nutgrass only has so much time and energy to make it through to sunlight. If it takes too long to get to the sun (penetrating the liner), then it will die.

Doing all three of the above things will greatly reduce the chance of nutgrass growing through your pool liner. One or two of these things will help a lot, but doing all three is magic.


Here in Central Florida, I have seen nutgrass as far as eighteen inches in the ground. This is super rare and typically going down even one foot will remove any nutgrass in the earth.

Many semi-inground installs will go down about half the height of the pool or 2-2.5ft. If you are doing this, don’t worry about nutgrass. It doesn’t exist that far in the earth.


If you read above, then you know that nothing is a guarantee for preventing nutgrass from growing through a liner except concrete. But some people just don’t hear this. After me telling them that, they still ask “OK but what about this or that”? Here then is a list of materials that people ask me about anyway that DO NOT necessarily prevent nutgrass from poking through the pool’s liner.

1 A two, three, or four-inch layer of mason or sugar sand

2 A liner guard/pad

3 Liquid nutgrass killer

4 Expensive foam boards(that are taped together to make a pool bottom)

5 A gallon of Round-up

6 Visqueen or plastic sheeting

7 Weed block

8 Hard base material – Some will think they need to add a hard material as a base so their pool won’t settle. This is not only unnecessary to prevent settling, it also won’t prevent nutgrass from grow up and through your liner.


Typically, nutgrass isn’t an issue. Most will put down a nutgrass killer or a pad and it will help a little if this persistent weed is in their yard. If you get a blade or two that grows through the liner, it surely sucks but is really not a big deal and easy to fix.

Some yards will have a lot of nutgrass though. I have seen pools with hundreds of blades growing through the liner and it looks like a rice field. That is not good.

If, while you are installing your above ground pool (or having it installed), you identify nutgrass in the ground, make sure and take the above extra steps. Whenever I see nutgrass before my install, I will at least apply double the granular chemical I use to kill it. That chemical is expensive, but it’s worth not having the pool get a bunch of blades of grass grow through the liner a few days later.


Dan writes with the knowledge of having 35 years (and counting) in the above ground pool industry.

21 thoughts on “How to prevent nutgrass from growing through your above ground pool liner

  1. Dan,
    I really appreciate the information that you have shared. What brand or key ingredient granular herbicide do recommend buying to use to put down before the pool is installed?

    1. Carsoron 4g is the herbicide, but you may not find it smaller than in 25lb bags. Zap Zit is a product for above grounds that you can buy for it though that comes in 2 pounds bags.

  2. So now that it’s too late and I already have at least a dozen blades poked through the line or do I just live with it? I truly feel that the installer should have done a better job. Is he responsible or liable for this the pool is less than a week old.

    1. That really sucks. So sorry. A dozen blades is a lot. I would probably remove and patch them and then see if more grow through. If more do, then I would consider changing the liner.

      I know you would like to put some blame on the installer. That is very common and I understand. The installer is not liable though for nutgrass damage unless they signed a contract saying that they are. And I’ve never heard of that.

      It’s a big expense to change the liner, so I would try to save it first. When this happens to one of my installs(which is rare, but does happen), I will offer a discount for changing the liner out. This may not sound like much or enough, but keep in mind that I(the installer) am not to blame or at fault for this. It’s just an unfortunate natural circumstance.

  3. Can I use granular nut grass killer as a pre-emergent in the lawn grass around my pool without killing the lawn grass ? If so, what kind do you recommend ?

  4. I have tons of nut grass coming through my liner. I am losing so much water a day. I have some one coming out to give me an estimate to replace my liner. Your information has been so helpful. What kind of barrier do you suggest after i put down the chemical to help this not happen again before they put the new liner in? It started to grow immediately after we had it installed.

    1. Just a liner guard to help create a better layer of preemergent to kill the nutgrass. Put it down right after you apply the nutgrass killer. Apply double the recommended dosage. Also, I highly recommend leaving the ground open a week or so before installing the new liner. This will give you a chance to identify the nutgrass beforehand and making sure you have it out of the ground.

  5. i did not know anything about nut grass till i installed a 16 ft round above ground pool. i dug up my sparsely covered area about 3-4 inch and removed the sod here in west central Florida, i put down 3-4 inch’s of processed sugar sand very soft sand. it leveled well i put down a liner installed an above ground pool and 9 days later nut grass growing through the liner. i drained the pool and marked 5 spots with a Sharpe that the nut grass grew through. i am now going to make a circular form to poor a 3 inch concrete slab on top of the sugar sand. Question should i put down the nut sedge granular kill to stop any growth ?
    i am also putting 15 mil plastic sheeting under the concrete as it should be with al concrete poors directly on the ground and adding steel wire mesh to help with preventing any future cracking and in the concrete i will be adding fiber again another preventative for long term cracks or break. any other advise on this would be appreciated thank you Douglas

      1. Update i completely took down my pool due to having 5 spots where the nut grass grew through. within 4 days it popped up in another 10 more places good thing i did not try to just spot kill and patch. Now that i have decided to poor a concrete slab with fiber added and a wire mesh. I know this will not guarantee it will not crack. If it does crack the nut grass will have a path so as an added preventative what granular nut grass killer should i use ? in this post you showed a pic of Gordon’s sedge stop but you did not specify which one you use. i can get this locally or through Amazon. Thank you Douglas

        1. Although in theory, nutgrass can grow through a crack in a concrete slab, I would not at all worry about that. The odds of that happening are crazy. Like winning power ball lottery odds or something. If you pour a concrete slab for your pool, you will be good.

    1. i feel your pain there is a solution you either have to do the work your self or pay someone else there price. lucky for me i am able to build my own form and lay out the concrete from a delivery of concrete its not easy believe me. but this solution is what i did for my fix it my not be the same for you.

  6. i was hoping to post a picture of the newly poured concrete slab i poured for the solution to the nut grass i had in my pool 2 months ago. it been 21 days since i poured the slab so this weekend i will set the pool up. to help with the liner on the abrasive concrete i am going to put 1 inch insulation 4×8 sheets duct taped together for a little bit of a softer feel on the feet. on top of the insulation i will also be putting down a Rhino pool pad that i had already bought when i had first put my pool up.

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