How to Get Rid of Bermuda Grass in Flower Beds and St. Augustine Lawns
- Bermuda spreads by both above-ground stolons and underground rhizomes, which is why it’s so hard to remove completely.
- In flower beds, selective grass herbicides such as fluazifop can control it without harming most ornamentals, used per the label.
- LSU AgCenter says there are no effective selective herbicide options for common Bermuda grass in St. Augustine.
- For severe infestations, LSU describes killing all vegetation with glyphosate and resodding at least two weeks later.
- Mowing St. Augustine too low gives Bermuda a competitive advantage, so correct mowing height is the main defense.
- How to identify Bermuda grass
- Why Bermuda is so hard to remove
- Removing Bermuda from flower beds
- Bermuda inside a St. Augustine lawn: the honest answer
- When renovating the lawn makes sense
- What not to do
- Other lawn grasses have more options
- Mowing height: why Bermuda wins in some lawns
- Keeping Bermuda out
- Frequently asked questions
It started as a few fine, wiry runners creeping out of the lawn edge. Now it’s woven through the azaleas, poking up through the mulch, and spreading into the St. Augustine in thin, darker-green patches that look nothing like the rest of the lawn. Bermuda grass is one of the most persistent invaders in Louisiana yards, and getting it out depends a great deal on where it’s growing.
At TurnKey Lawn Care, weed control and bed maintenance are part of the care we provide across the metro. If Bermuda has moved into your beds or lawn, request a free estimate and we’ll give you a straight answer about what will and won’t work.
This guide covers how to identify Bermuda grass, why it spreads so well, how to remove it from flower beds, what your realistic options are inside a St. Augustine lawn, and how to keep it from coming back.
How to identify Bermuda grass
The LSU AgCenter home lawn series describes common Bermuda grass as having compact, fine-textured, sharply pointed leaves ranging from light to dark green. Where the leaf meets the stem, there’s a ring of small white hairs. Its seedheads are distinctive. LSU describes three to seven spikes arranged like fingers, carrying tiny pink to purple flowers. In a St. Augustine lawn, Bermuda stands out once you know what to look for:
- Much finer blades than St. Augustine’s broad, flat leaves
- Thin, wiry runners that creep across walks and into beds
- Patches that look denser or a different shade of green from the surrounding lawn
- Finger-like seedheads in summer, often standing above the St. Augustine
- Growth concentrated in the sunniest parts of the lawn and along hot pavement edges
Why Bermuda is so hard to remove
LSU explains that Bermuda spreads through strong stolons, which are above-ground stems, and rhizomes, which are underground stems, both of which can root and spread sideways. That double system is the problem. Pulling what you can see leaves the rhizomes in the soil, and each piece can send up new growth. Tilling can make it worse by chopping rhizomes into many pieces that each root again. It’s also why Bermuda moves so easily from the lawn into beds. Runners creep across the soil surface and under edging, while rhizomes travel underneath and surface in the middle of a planting.
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Removing Bermuda from flower beds
Flower beds are where you have the most options, because there’s no lawn grass to protect. An LSU AgCenter article points to selective herbicides for controlling grassy weeds, including Bermuda and crabgrass, in flower beds. It names products such as Grass-B-Gon, whose active ingredient is fluazifop-P-butyl, and Hi-Yield Grass Killer. These products target grasses and leave most broadleaf ornamentals unharmed, but they’ll injure any lawn grass they reach. Check the label for the specific plants in your bed, and keep the spray off the lawn edge. A still, dry morning with no wind is the safest time to apply it near turf. A practical approach for a Bermuda-infested bed:
- Identify it. Confirm the grass is Bermuda and not another grassy weed like nutsedge, which needs a different product.
- Treat actively growing Bermuda. Apply a selective grass herbicide labeled for use around your ornamentals, following the label exactly.
- Repeat as the label allows. Established Bermuda often regrows from rhizomes, so follow-up applications are common.
- Remove what’s left. Dig out rhizomes by hand in soft soil once the plants have weakened.
- Refresh the mulch. A fresh layer of mulch makes new shoots easier to spot and pull.
- Install a proper edge. A deep, well-set edge between lawn and bed slows runners from creeping back in.
Our pages on mulch installation and bed maintenance and flower bed design and planting cover keeping beds clean once the Bermuda is out.
Bermuda inside a St. Augustine lawn: the honest answer
This is the hard case. LSU states plainly that there are no effective selective herbicide options for managing common Bermuda grass in St. Augustine. In other words, there isn’t a spray that kills the Bermuda and leaves the St. Augustine alone. Products that control grassy weeds in other lawns will injure or kill St. Augustine too. That leaves a few realistic paths, depending on how much Bermuda is in the lawn:
| How much Bermuda | Realistic option |
|---|---|
| Scattered small patches | Correct the mowing height and feeding so St. Augustine can outcompete it, and dig out small patches by hand |
| Larger patches | Spot-kill the patch with a non-selective herbicide per the label, then replant that area with St. Augustine sod or plugs |
| Severe infestation | Renovate: LSU describes killing all vegetation with glyphosate, preparing the site and installing new sod at least two weeks later |
A non-selective herbicide kills everything it touches, including the St. Augustine around the patch, so spot treatment means accepting a bare area that needs replanting. Our post on getting St. Augustine to spread covers filling those areas afterward.
When renovating the lawn makes sense
Starting over is a big decision, but for a lawn where Bermuda has taken a large share of the ground, it’s often the only route to a clean stand of St. Augustine. LSU describes the approach for severe infestations: apply a non-selective herbicide such as glyphosate to kill all vegetation, then prepare the site and install new sod at least two weeks after the application. What a renovation involves in practice:
- Treat the whole area with a non-selective herbicide, following the label, while the Bermuda is actively growing
- Check for regrowth and retreat any green shoots, since Bermuda rhizomes can survive a single application
- Wait at least two weeks after the application, as LSU advises, before preparing the site
- Remove the dead material, test and prepare the soil, and grade for drainage
- Install new St. Augustine sod, inspecting each pallet for Bermuda before laying it
Renovation is best timed for the growing season, so the Bermuda is actively growing when it’s treated and the new sod roots in quickly afterward. Our posts on preparing soil for sod and laying sod over existing grass cover the steps between killing the old lawn and installing the new one.
What not to do
A few common approaches waste time or make the problem worse:
- Pulling runners in the lawn without dealing with the rhizomes, which regrow
- Tilling a Bermuda-infested bed or lawn, which can scatter rhizome pieces that root again
- Spraying a bed grass killer near the lawn edge, where drift can damage the St. Augustine
- Scalping the lawn, which hands Bermuda the advantage LSU describes
- Laying new sod over Bermuda without killing it first
Other lawn grasses have more options
St. Augustine is the difficult case. LSU notes that in centipede grass, sethoxydim suppresses Bermuda, and in zoysia, a herbicide containing fenoxaprop and triclopyr will suppress it. Suppression isn’t the same as elimination, so repeat treatments and good cultural care still matter. Confirm the product label covers your lawn grass before using anything, since the wrong product on the wrong grass causes serious damage. Our pages on Bermuda grass care and centipede grass care cover how each grass is maintained.
Mowing height: why Bermuda wins in some lawns
LSU points to a specific cause of Bermuda invasion: mowing St. Augustine lower than the recommended height gives a competitive advantage to Bermuda, which tolerates low mowing. St. Augustine is best kept at 2.5 to 3 inches, according to LSU. Scalping it to 2 inches or less weakens the St. Augustine while suiting the Bermuda perfectly, and over a few seasons the balance tips. Raising the mower is the single most useful change for a lawn with scattered Bermuda. It won’t remove what’s already there, but it shifts the competition back toward the St. Augustine, and a denser lawn leaves the Bermuda less room each season. Our page on how short to cut St. Augustine explains the right height.
Keeping Bermuda out
LSU’s general advice for weed prevention is to maintain a healthy lawn through regular mowing, proper fertilization and soil pH management, which produces dense, vigorous turf that competes well with weeds. For Bermuda specifically, a few habits help:
- Keep St. Augustine at 2.5 to 3 inches and never scalp it
- Feed according to a soil test so the lawn stays dense
- Maintain a clean, deep edge between lawn and beds
- Pull runners crossing into beds before they root
- Inspect new sod for Bermuda before it’s laid
That last point comes from a UF/IFAS Extension tip, which recommends removing any sod pieces infested with Bermuda during installation so it doesn’t take over a patch of the new lawn.
Frequently asked questions
What kills Bermuda grass but not lawn?
It depends on the lawn. LSU AgCenter says there are no effective selective options for Bermuda in St. Augustine, while sethoxydim suppresses it in centipede and a fenoxaprop and triclopyr product suppresses it in zoysia. Always confirm the label covers your grass.
What kills Bermuda grass but nothing else in flower beds?
Selective grass herbicides such as fluazifop-P-butyl, sold in products like Grass-B-Gon, control Bermuda and other grassy weeds in beds without harming most broadleaf ornamentals. Check the label for your specific plants and keep it off the lawn.
Is Bermuda grass difficult to get rid of?
Yes. LSU AgCenter explains that it spreads by both stolons above ground and rhizomes below, and both can root and spread, so pieces left in the soil regrow. Repeat treatments and follow-up digging are usually needed.
Can you kill Bermuda in a St. Augustine lawn?
Not selectively. LSU AgCenter says there are no effective selective herbicides for Bermuda in St. Augustine, so the options are outcompeting it with correct mowing and feeding, spot-killing and replanting patches, or renovating a severely infested lawn.
Why is Bermuda taking over my St. Augustine?
The most common reason is mowing too low. LSU AgCenter notes that mowing St. Augustine below its recommended height gives Bermuda a competitive advantage, since Bermuda tolerates low mowing.
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