How to Stop Weeds and Grass from Growing Under Your Pool

One of the most frustrating things about setting up an above-ground pool is what happens beneath it. You spend a sunny afternoon leveling the ground and filling the pool, only to notice a few weeks later that determined blades of grass and stubborn weeds are pushing up against the liner. It’s a common headache that can make any pool owner worry about damage, leaks, and an endless battle with nature. The good news is that stopping weeds and grass from growing under your pool is entirely possible, and with a little know-how, you can prevent the problem before it starts or tackle it even if your pool is already full of water.

When we talk about growth under a pool, we’re really dealing with the incredible resilience of plants. Grass and weeds need light, air, and a way to reach the surface. The weight of a pool filled with thousands of gallons of water does a great job of smothering most vegetation, but some plants are persistent enough to send up pale, white shoots that search for the tiniest gap between the liner and the ground. While those shoots rarely puncture a pool liner on their own, they can create small bumps, cause the liner to stretch unevenly, and provide hiding spots for moisture that encourages mold or mildew. Over time, the roots can even work their way into the seams if the liner isn’t perfectly smooth, shortening the life of your pool.

The absolute best time to stop weeds and grass is before the pool goes up. If you’re planning a new installation, think of ground preparation as an investment in years of hassle-free swimming. Start by marking out a circle that’s at least a foot larger than your pool’s footprint. Then remove all the vegetation in that area—not just cutting the grass down to the dirt but getting rid of the sod and the root layer entirely. A flat shovel or a rented sod cutter makes quick work of this. By stripping away that top layer of roots and rhizomes, you’re eliminating the very things that could try to regrow. Level the exposed soil carefully, because any depressions or high spots will become more obvious once the liner is stretched over them.

Once the ground is bare and level, it’s tempting to just place the pool right on the dirt, but that’s a shortcut you’ll likely regret. Instead, put down a heavy-duty weed barrier. Unlike the thin landscaping fabric you might use in a flower bed, look for a geotextile ground cloth specifically designed for use under pools, or at least a thick, woven polypropylene landscape fabric. Avoid plastic sheeting, which can trap water and create a slick, wrinkled surface. The fabric works by blocking light completely while still allowing moisture to drain away, so any dormant seeds in the soil never get the signal to sprout. Lay the fabric over the entire prepared area, overlapping seams by at least six inches, and secure it with landscape staples so it doesn’t shift when you set up the pool.

On top of the barrier, many pool owners like to add a layer of sand or a commercial pool pad. A smooth, two-inch layer of mason sand creates a soft cushion that protects the liner from any small rocks or roots and helps with drainage. Some people sprinkle a little bit of rock salt over the sand before placing the liner because salt can discourage root growth, but use this trick sparingly and never directly against the vinyl if your pool has a metal frame that could corrode. If you want a completely eco-friendly alternative, a thick layer of cardboard covered by sand will eventually break down, but it serves as an excellent initial barrier that smothers anything trying to grow.

What if your pool is already set up and you’re seeing those annoying sprouts pop up around the edges or right where the cove meets the ground? You can still manage the situation without draining the pool. The most straightforward approach is to pull the weeds by hand or trim them as close to the ground as possible. Because the area under the pool is dark and compressed, many weeds will weaken and die if you persistently remove any green growth that manages to peek out. Follow up by placing a heavy layer of mulch, gravel, or pavers around the perimeter of the pool, overlapping the edge of the liner. This blocks the last bit of light and creates a neat, finished look that deters new weeds from sneaking in from the sides.

For stubborn runners like Bermuda grass or nutsedge that seem to find their way under the wall, you can use a non-selective herbicide very carefully. Pick a product that becomes inert once it touches the soil, such as a glyphosate-based weed killer, but apply it only with a shield or a small brush directly onto the leaves of the offending plants. Never spray near the pool when the pump is running, because even a tiny drift of chemical can find its way into the water. Many homeowners prefer a natural solution, like pouring boiling water over the weeds or spraying them with a strong vinegar solution on a hot, sunny day. These methods kill the foliage and eventually exhaust the roots, though you may need to repeat the treatment a few times. Again, remember that anything you apply to the ground near the pool should be kept away from the water itself to keep swimmers safe.

Another trick that works surprisingly well for borders is to install a physical edging barrier around the pool base. Aluminum or heavy plastic edging buried a few inches deep will block horizontal root runners that travel just under the surface. Pair the edging with a ground cover of river rock, which looks tidy and absorbs heat without encouraging weed seeds to settle. The combination of shade from the rock, the physical block of the edging, and your regular maintenance will create a zone where weeds simply can’t survive.

The most important thing to remember is that consistency beats brute force. Even the best preparation won’t make your yard a sterile bubble forever, because wind and birds will inevitably drop a few weed seeds onto the soil around the pool. Take a walk around your pool once a week with a hand weeder or a small hoe and pop out any volunteers while they’re still tiny. A little regular attention prevents the big, tangled mess that seems so overwhelming later.

Ultimately, preventing weeds and grass under your pool is about layering strategies: remove the existing plants, block light with a sturdy barrier, maintain a dry and inhospitable border, and stay on top of any new growth. Whether you’re building a brand new backyard oasis or just trying to calm down the jungle that has crept up on last summer’s pool, a mix of good ground prep and ongoing care will keep your liner smooth, your water clean, and your weekends free from weeding chores. A pool is meant for relaxing, and with the right underlayment and a watchful eye, you can spend more time floating and less time fighting nature.