Permanently removing St. Augustine grass requires killing both the visible turf and its extensive network of above-ground runners, then following up to catch any regrowth before the grass re-establishes. A single pass with herbicide or a single weekend of labor almost never finishes the job. The grass spreads through thick stolons that root at every node, and even a short surviving segment can regenerate an entire patch within a season. Getting rid of it for good means committing to a multi-step process over several weeks, and the method you choose depends on how much time you have, whether you’re comfortable using chemicals, and what you plan to put in its place.
Why St. Augustine Grass Is So Hard to Eradicate
St. Augustine grass rarely produces viable seed in a managed lawn. Instead, it spreads almost entirely through stolons, the thick, fleshy runners that creep along the soil surface, sending down roots and pushing up new leaf blades at each node. This growth habit is what makes the grass popular for quickly filling in bare spots, but it’s also what makes removal so frustrating. A single stolon fragment left behind in the soil or tucked under a landscape border can quietly take root again. Unlike bunch-type grasses that die when the central plant is killed, St. Augustine treats every node as a potential new plant.
The stolons themselves are also tougher than they look. They store water and carbohydrates, which means they can survive brief droughts, shallow tilling, and even a light herbicide application that only scorches the leaves. If the runners aren’t killed all the way through, the grass bounces back. This is why every method below emphasizes follow-up treatment or physical removal of the stolon network, not just the green top growth.
Using Glyphosate to Kill St. Augustine Grass
Glyphosate-based herbicides are the most common chemical approach. Glyphosate is a non-selective systemic herbicide, meaning it kills virtually any plant it contacts and works by being absorbed through the leaves and translocated down into the roots and stolons. For St. Augustine grass, this systemic action is critical because you need the chemical to reach the entire stolon network, not just burn the leaf tips.
A typical approach works like this: mow the lawn slightly shorter than usual a few days before application so the grass is actively growing but not so tall that spray can’t reach the lower canopy. Then apply a ready-to-use or concentrated glyphosate product on a calm, dry day when rain isn’t expected for at least 24 hours. The grass will begin yellowing within a week and should look fully brown within two weeks. Here’s the part most people skip: wait another week or two and inspect the area carefully. Any green stolons or fresh green shoots need a second application. Two full applications spaced about two to three weeks apart are standard for St. Augustine, and some particularly vigorous stands need three.
Timing matters. Glyphosate works best when the grass is actively growing and metabolizing, which for St. Augustine means late spring through early fall in most of the southern United States. Applying it when the grass is semi-dormant from cool temperatures or drought stress dramatically reduces how much chemical the plant takes up, and you’ll see incomplete kill. If your St. Augustine has gone brown in winter, wait until it greens up in spring before starting treatment.
Solarization as a Chemical-Free Alternative
If you’d rather avoid herbicides entirely, soil solarization is the most effective non-chemical method for killing St. Augustine grass over a large area. The idea is straightforward: cover the grass with clear plastic sheeting and let the sun cook it. On a sunny stretch of days, temperatures under the plastic can reach well above the threshold that kills grass tissue and the stolons beneath.
To solarize effectively, mow the grass as short as your mower allows, water the area thoroughly so the soil is moist (moist soil conducts heat better than dry soil), then lay clear plastic sheeting directly on the ground. Thicker sheeting, around 2 to 4 mil, holds up better in wind. Anchor the edges with soil, bricks, or landscape staples so no air gets underneath. Leave the plastic in place for four to eight weeks during the hottest part of summer. In the Deep South or Gulf Coast regions where St. Augustine is most common, summer sun is intense enough to kill the grass and many of the stolon nodes within six weeks.
Solarization has two advantages beyond being chemical-free. First, the heat also kills weed seeds and some soil pathogens near the surface, giving you a cleaner slate for replanting. Second, it breaks down the dead plant material somewhat, making it easier to rake out or till in afterward. The drawback is time. You’re committing a large section of your yard to being under plastic for a month and a half during the season when you’d most want to use it.
Sheet Mulching for Smaller Areas
Sheet mulching, sometimes called lasagna mulching, smothers St. Augustine grass by blocking all light and air. Lay overlapping sheets of cardboard directly on the mowed grass, wet the cardboard thoroughly, then pile on four to six inches of wood chip mulch or compost. The grass and stolons underneath die from light deprivation over the course of several weeks, and the cardboard eventually breaks down into the soil.
This method works well for converting a section of lawn into a garden bed or a mulched landscape area. It’s less practical for killing an entire lawn because of the volume of materials needed and because you can’t easily seed or sod new grass through a thick cardboard-and-mulch layer. If your goal is to replace St. Augustine with a different turfgrass, solarization or glyphosate are more realistic paths. If your goal is to replace it with garden beds, shrub plantings, or a mulched area, sheet mulching does double duty by killing the grass and building your new planting surface at the same time.
One important detail: don’t use black plastic as a substitute for cardboard in a permanent bed. Black plastic blocks water and air exchange with the soil, which kills the grass but also degrades the soil biology you’ll need for healthy plantings later. Cardboard is the better choice because it smothers the grass while still allowing moisture and microbial activity to continue underneath.
Manual Removal by Cutting Out the Sod
For smaller areas or situations where you need the grass gone immediately, physically cutting it out is the most direct approach. A sod cutter, which you can rent from most equipment rental shops, slices beneath the grass at root depth and rolls the turf up in strips. This removes the stolons, the root zone, and the leaf canopy in one pass.
The challenge with manual removal is thoroughness. St. Augustine stolons can extend several inches beyond the visible edge of the turf, and any fragments left in or on the soil will attempt to re-root. After cutting out the sod, rake the area carefully and pick out every visible piece of stolon. Then water the bare soil and wait a week or two. Any regrowth that appears can be spot-treated with glyphosate or pulled by hand before it re-establishes.
Sod cutting is hard physical labor, especially in clay-heavy southern soils. It generates a lot of material that you’ll need to dispose of or compost. But it gives you a clean start faster than any other method, since you can begin replanting within days rather than waiting weeks for chemicals or solarization to finish working.
Why Tilling Alone Usually Fails
A common instinct is to rototill the entire area and assume the chopped-up grass will die. With St. Augustine, tilling alone usually makes the problem worse. Every stolon node that gets separated and redistributed through the soil becomes a potential new plant. You’re essentially propagating the grass rather than killing it. If you’ve ever seen St. Augustine runners take root from a single dropped clipping, you understand the risk.
Tilling can be a useful part of the process, but only after the grass is already dead. Once you’ve confirmed a complete kill through herbicide, solarization, or sod removal, tilling the dead material into the soil helps break it down and improves the seedbed for whatever you plant next. The sequence matters: kill first, till second.
Replanting After the Grass Is Dead
Once St. Augustine grass is fully dead and the area is cleared, you’ll likely want to plant something new fairly quickly to prevent weeds from colonizing the bare soil. If you used glyphosate, the good news is that the herbicide binds tightly to soil particles and does not leave a residue that prevents new seed from germinating. Research on turfgrass species has confirmed that glyphosate applied to soil before seeding causes little effect on seed germination, so you can seed a new lawn shortly after the old grass is dead and any residual chemical has dried.1Cambridge University Press / Weed Science. Germination of Seeds of Turfgrasses as Affected by Glyphosate and Paraquat
How soon you can replant depends on your method. After glyphosate, most turf professionals recommend waiting at least two weeks after the final application before seeding or sodding, mainly to confirm the old grass is completely dead rather than because of chemical residue. After solarization, you can plant as soon as you remove the plastic and prepare the soil. After sod cutting, you can often lay new sod the same day if the soil is level and in decent condition.
If you’re switching to a different warm-season grass like bermudagrass or zoysiagrass, plan the kill for late spring so you can plant the replacement during peak warm-season growing months. If you’re switching to a cool-season grass like tall fescue (realistic only in the upper transition zone), time the kill for midsummer so you can seed in early fall when cool-season grasses establish best.
Dealing With Stolons That Creep In From Neighbors
Even after a perfect kill, St. Augustine grass from an adjacent property can send stolons across a shared property line and recolonize your yard. This is one of the most frustrating aspects of removal because it’s an ongoing maintenance issue, not a one-time project. A physical barrier is the most reliable long-term defense. Steel or aluminum landscape edging buried three to four inches deep along the property boundary will intercept most creeping stolons before they cross over. Concrete walkways, driveways, and curbing serve the same function.
Without a barrier, you’ll need to patrol the border regularly during the growing season and either pull invading runners by hand or spot-spray them with glyphosate before they put down roots on your side. Catching them early is the key. A runner that’s been growing into your yard for a month has already rooted at multiple nodes and is much harder to fully remove than one caught in the first week or two.
When Disease Does the Work for You
Occasionally, St. Augustine grass dies on its own from disease, and homeowners wonder whether they should just let the disease finish the job rather than intervening. Take-all root rot, caused by the fungal pathogen Gaeumannomyces graminis var. graminis, is one of the most damaging diseases of St. Augustine and other warm-season turfgrasses. It’s most severe following periods of high rainfall on stressed turf, producing yellow patches that expand as the roots rot and the grass loses its ability to take up water.2EDIS. Take-all Root Rot
While take-all root rot can devastate large swaths of St. Augustine, relying on it as an eradication strategy is unpredictable. The disease tends to move in patches, leaving pockets of surviving grass that recover once conditions change. It also doesn’t kill stolons consistently enough to prevent regrowth. If disease has already weakened your St. Augustine significantly, it does make the follow-up work easier. Weakened grass responds to glyphosate more quickly and is easier to pull or cut out physically. But waiting for disease alone to provide a permanent kill would likely mean years of watching an ugly, patchy lawn that never quite finishes dying.
Common Mistakes That Lead to Regrowth
Most failed attempts at killing St. Augustine grass share one or more of these errors:
- Single application: Applying glyphosate once and assuming the job is done. St. Augustine stolons are thick and can survive a single pass, especially if the application rate was light or conditions weren’t ideal. A second pass two to three weeks later is standard practice.
- Spraying during dormancy: Applying herbicide when the grass is brown or semi-dormant from cold or drought. The grass isn’t actively translocating chemicals to its root system and stolons, so much of it survives.
- Skipping stolon removal: Killing the grass chemically but leaving the dead mat in place without checking for live stolons underneath. Dead leaf blades can hide green, living runners that re-emerge weeks later.
- Ignoring edges: Treating the main lawn area but not the runners that have crept under fences, into flower beds, or along sidewalk cracks. These survivors recolonize the cleared area within a season.
- Tilling too soon: Rototilling before confirming a complete kill, which spreads live stolon fragments throughout the soil.
Avoiding these mistakes comes down to patience and follow-through. Budget four to six weeks for the full eradication process if you’re using herbicide, and up to eight weeks if you’re solarizing. Inspect the area multiple times before you declare victory and start replanting.
Selective Herbicides and St. Augustine in Mixed Lawns
The discussion so far assumes you want to kill all the St. Augustine in a given area. But what if St. Augustine has invaded a bermudagrass or zoysiagrass lawn and you only want to remove the invader without harming the desirable grass? This is a harder problem. Glyphosate is non-selective, so it will kill whatever grass it touches. You’d need a selective herbicide that targets St. Augustine while leaving your preferred grass unharmed.
Options here are limited. Some products containing the active ingredients fluazifop or sethoxydim can selectively suppress or kill St. Augustine grass in bermudagrass or zoysiagrass lawns, though effectiveness varies and multiple applications are usually required. These are grass-on-grass herbicides, meaning they exploit differences in susceptibility between grass species, and results depend on the health and density of both the target grass and the desirable grass. Read labels carefully, because some formulations that are safe on bermudagrass will damage zoysiagrass, and vice versa.
For lawns where St. Augustine has only invaded along borders or in patches, spot-treating with glyphosate using a sponge applicator or a shielded sprayer lets you kill the St. Augustine without spraying the surrounding grass. It’s tedious, but for limited invasion it can save you from having to redo the entire lawn. Wipe the glyphosate directly onto the St. Augustine leaves, being careful not to drip onto adjacent turf, and repeat on any regrowth you see over the following weeks.