Nut Grass Pool Liner

Help There is Grass Growing in My Pool!

This isn’t a fun pool moment. Picture the scene. You’re happily cleaning your fairly new above ground swimming pool getting it ready for the weekend. As you run the vacuum across the pool, you notice something sticking to the bottom. You try to suck it up, but it is stuck. Then you look closer. “What is that? That looks like a blade of grass. Is that growing through the liner?” You let the water settle to get an even better look. “That IS a blade of grass growing through my pool liner!” Your happiness is replaced with a sinking stomach and your mind explores the worst possible scenario with questions like, “How did this happen? Is grass going to grow everywhere in my pool? Can this be fixed? Am I going to need a new liner? Will I have to drain the pool?” With the adrenaline pumping slightly, you stop cleaning the pool and quickly go on the Internet. Through searching the web you eventually find this blog and when you read the next heading, you breathe your first sigh of relief.

Nutgrass Will Not Destroy Your Above Ground Pool Liner

Nutsedge or nutgrass is a persistent weed. When in its growth stage, it grows upward forming a needle-like point that is strong enough to grow through asphalt. A pool liner is no match for the nutgrass as it pushes toward the sun with its super strong point. So the result is it grows straight through the liner of your pool. There can be anywhere from just one or two blades all the way up to a couple hundred blades. This depends on how much nutgrass is in the soil underneath the spot where you have installed the pool.

Usually only a few blades grow through the liner, but there can be more. Over the years I’ve seen extreme cases of nutgrass intrusion that amounted to a hundred or more blades growing everywhere on the bottom of a single pool. It’s a very odd sight when you look into a pool and it has perfectly healthy, green grass growing in the water. I said earlier that nutgrass won’t ruin a liner, but in extreme cases where there are too many blades growing through it’s best to replace the liner. Partly because it’s a lot of work to patch them all and partly because you’ll want to treat the soil underneath so the nutgrass doesn’t reappear.

Getting Rid of Nutgrass in Your Pool

I get it. This is all good info and everything, but you want to know how to fix this. OK, so the first thing
you’ll have to do is drain your pool. JUST KIDDING. You do not have to drain your pool to get rid of nutgrass. The hole the grass has made can be patched underwater.

Here’s what you will need to get rid of nutgrass:

  • An underwater vinyl patch kit
  • A small pair of clippers
  • A dropper used to administer ear-drops or larger syringe needle
  • Some liquid weed killer (like Roundup)
  • Scissors
  • A dive mask and weight belt would be nice
  • A bathing suit ’cause you’re going to get wet

So here are 10 steps that explain exactly what to do:

  1. Open your patch kit, read the directions and then cut some patches the size of a 50 cent coin using a pair of scissors. Place the vinyl patches and the provided glue on the pool’s top rail so that you can get to them from inside the pool.
  1. Fill your syringe or ear dropper with the liquid weed killer (Roundup) and place it on the pool’s top rail next to your patches so that you can again have access to it from inside the pool.
  1. Place the clippers, dive mask, and weight belt on the top rail for the same reason.
  1. Put on your bathing suit (optional) and get into the pool.
  1. Now that you’re in the pool, put on your mask and belt, grab the clippers and swim to where the nutgrass is growing on the bottom.

Real pool guy tip: If you don’t have a weight belt, it will to be harder because your body is going to try to float up while you are on the bottom of the pool. If you have a helper, he/she can gently hold your body down with his/her foot. If you don’t have a helper, emptying your lungs of air by exhaling slowly will keep you on the bottom of the pool more effectively and you won’t float up as much.

  1. Once at the site of the grass blade, clip the grass at the base and leave the clippers down there on the spot and return to the surface.

Note: Leaving the clippers on the bottom at the site of the grass blade that you have clipped will ensure that you will find it again when you go back down. It would really suck if you lost the spot.

  1. Once you’ve returned to the surface, take one patch, dab some vinyl glue on one side of the patch, fold it in half and take it with you and return to the spot where you have clipped the nutgrass. Also, take the weed killer applicator with you to the bottom.
  1. When you get back to the site of the hole, quickly shoot some weed killer into the hole and immediately unfold the patch and press the glued side down over the hole. Repeatedly press the patch in place, making sure it’s nice and flat and sticks to the liner nicely and evenly.
  1. Grab your clippers and injector and return to the surface again. You’re done!
  1. Pat yourself on the back, because it’s fixed.

There you go. See how easy that was? Now you can go back to getting ready for the weekend’s big pool party. No one will notice that you got all stressed and had to fix the pool, unless you tell them.

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30 thoughts on “Help There is Grass Growing in My Pool!

  1. I have bees flying around us when we get in. I hate to kill them, I put til lamps to see if the smoke wouldn’t keep them away but it don’t anyone have any helping ideas, and I also have grass coming up in my liner ugggh

  2. I was told AFTER I put my pool up and filled it, that after you make the bed for your pool to set on, to sprinkle a fairly heavy amount of salt all throughout the sand, and that will kill any vegetation that might try to grow up through the poll. Has anybody ever tried this?

    1. Not sure about SALT, but know a person that sprayed liquid detergent and vinegar mix on plants hoping to kill some weeds, but killed everything and nothing grew there for years.

  3. After a month of use we have a few nutgrass sprouts coming through the liner as well. I’ve gotta say, I’m hooked! How do I get more? I’d prefer a nice carpet like layer of St. Aug, but any grass will do. Should I poke holes in the liner where I want to plant seeds, or just keep trimming the nutgrass blades to encourage spreading? Thanks the advice!

    1. You do not want nut grass! It gets ugly as it gets taller. It is super invasive. It will take over everything! Its not soft to walk n either.

  4. Help!
    20 x 40 to ground pool, vinyl liner. Haven’t opened pool in 5 years, but everything was working before my husband died. The pool is not near the house, and o neglected to keep leaves off the top of a very expensive cover. I looked put the other day and if I put a Japanese bridge over it I would have Monet’s Garden, saving me a trip to France. I plan to put house on market in next 6 months. Have the roots gone through the cover? Do I get the pool people to pull it off, dispose of it, get a cheap cover for selling purposes? Just open the pool and put off getting a cover until after the season is over? I do not have much money to put into this project!!!! It will spell trouble if potential buyers see it!



  5. I’m freaking out over this Nutsedge topic, as my backyard is riddled with it. We just bought an Intex Ultra Frame 16 x 48 round. We have not yet put it up. I have reading and reading and reading about ways to prevent this from happening to ours. Apparently nothing can keep the sedge down. I’m trying to dig out all of the tubers I can possibly find and I’m making sure to use cover that will blackout the sun, as I know from experience that this grass won’t grow in shade. It loves moisture and sun. I’ve considered putting down clay cat litter under the sand and groundcovers I’m using to try and dry them out. The tubers look like teeny tiny little potatoes or, as they’ve named it “nut grass”, little nuts. They sit in the top 6 inches of your soil. They like dead soil that doesn’t drain well. Gardener sites have said that darkening or shading the area will weaken the plants and make them too soft to pierce our liners. But, you also want to dig these sedge plants/grass out and literally throw them away. Ugh, I’m scared. So, I am going to try and remove as many of these sedge plants and their tubers as I can and try to completely blackout the sun. But, they say not to use plastic, as to not let water stand in between your pool liner and the plastic cover. I purchased some industrial strength black weed barrier from Amazon that I’m going to layer over the sand and under the bottom tarp that came with my pool. This way water will drain properly. Wish me luck. I will return after awhile to see how this goes.

    1. We made a little round brick patio. In the summer I cover it in sand and set up the pool. In the fall it’s for our fire pit.

  6. I think he’s saying that the link you have in regards to patch kit sends you to one that cannot be used under water. Your article states you don’t have to drain pool to remove and patch due to weeds. I found one at pinch a penny for 9.99 that works underwater and no glue needed. Gonna try it this weekend.

    1. Hello I I’m curious to know if the patch worked for you I now have grass growing through mine as well.

  7. 2 weeks, liner has grass sprouts. I like the advice, will attempt. Not sure about my husband holding me underwater though????

  8. The article says you Don’t have to empty the pool. The grass is through the bottom and the kit doesn’t work underwater. Maybe I’m missing something.

    1. Dan’s answer:

      What “kit” are you using? The only vinyl patch kit that I am aware of is an underwater one. And the kit is really only a piece of clear vinyl (that you can cut in small sizes) and a tube of glue. The glued piece of vinyl will adhere to your liner under water. You of course have to pull out the grass first before you can patch. I would be interested to know what it is that you are talking about.

  9. Hello, I checked out the link to your vinyl repair kit because I have grass sprouts growing through my above ground pool liner. The pool is filled with water. Now, your advice said you can use this patch kit underwater, but the instructions on the patch kit says it CANNOT be used for underwater repairs. Is this true?

    1. Hello Victoria,
      The patch cannot be applied underwater but it can be used for tears below the waterline. The waterline would need to be lowered below the tear, the spot cleaned and then the kit can be applied. You can then raise the waterline once the kit has time to set.

  10. Since I can’t lift cover by myself and pool needs cover to keep bugs out, I made one from mosquito netting and elastic. Works well, just be sure to fold it over on itself when taking off. Bugs will just end up in the water otherwise.

  11. Enjoyed your humorous article on the grass in the pool. Well, actually that is about the only thing that has not happened to me yet. I bought my first ever above ground pool from Costco a few months ago and am having a terrible time. I hurt my back badly, and a few weeks later I have a green pool and mosquitoes so bad you will not believe. The shock took care of the green pool but what can I do to get rid of all these bugs and mosquitoes in my pool. Please help

    1. Hi. There is nothing that I’m aware of that prevents bugs from landing in a swimming pool. A green pool without the pump running can attract some but not a balanced running pool. A body repellent spray, citronella candles, or some kind of mosquito repellent appliance is all that I know of to help.

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