Key takeaway: There’s no selective herbicide that kills couch, kikuyu or buffalo while leaving another one of those grasses untouched, because all three are grasses and broadleaf herbicides only work on broadleaf plants. Winter grass is the exception: it’s a genuinely different, annual weed grass, and selective products safe on buffalo do exist for it. For a grass-versus-grass invasion, careful spot treatment or physical removal is the honest answer, not a bottle you haven’t found yet. If you actually want an entire lawn gone rather than one grass out of another, see our guide to killing grass before renovating or starting over instead.
If you’ve gone looking for a weed killer that removes couch or kikuyu from a buffalo lawn, or buffalo from a couch lawn, without a trace of collateral damage, you’ve probably noticed the advice online contradicts itself. That’s because the honest answer disappoints most people: no such selective spray exists, since couch, kikuyu and buffalo are all grasses, and the chemistry that lets a weed killer tell a grass from a broadleaf plant can’t tell one grass species from another. Winter grass is the one genuine exception in this cluster, since it’s a different kind of weed entirely and does have real selective options. Here’s what actually works for each.
Why There’s No Easy Spray for Grass-Versus-Grass
A selective broadleaf herbicide, the bromoxynil, MCPA and dicamba blends used against bindii and clover, works by exploiting a real biological difference between grasses (monocots) and broadleaf plants (dicots). Couch, kikuyu and buffalo are all grasses, so none of those products can distinguish between them, and neither can any other commercially available lawn herbicide sold to home gardeners. Products built around fluazifop-p-butyl, sometimes suggested online as a fix, are registered to remove grass weeds from garden beds and ornamental plantings, not to selectively kill one turf grass growing inside another. Using one that way is an off-label application the product’s own directions don’t support, and it’s done at the user’s own risk rather than the product’s.
How to Remove Couch, Kikuyu or Buffalo From Each Other’s Lawn
Since no selective option exists, the realistic methods are the same whichever direction the invasion runs, whether that’s kikuyu creeping into buffalo, couch creeping into buffalo, or buffalo creeping into a couch lawn:
- Act early. Once an invading grass covers more than roughly a quarter of the lawn, spot treatment stops being realistic and a full renovation is the more efficient path. Catching it as a small patch is what makes this approach work at all.
- Spot-treat with glyphosate, applied precisely. Paint or wipe it directly onto the leaf blades of the unwanted grass with a small brush, sponge or gloved hand, rather than spraying, since glyphosate kills whatever green tissue it touches and can move a short distance inside the plant it lands on.
- Lift runners clear before painting them. Where the invading grass is spreading by a runner or stolon, lift it up off the desired lawn before applying, so the chemical only contacts the plant you’re trying to remove.
- Time it to reduce collateral risk. Applying during the wanted lawn’s slower cooler-season growth reduces the chance of affecting it, even though the herbicide itself works best on actively growing tissue. It’s a trade-off, not a guarantee either way.
- Dig out what you can by hand, roots and runners included, particularly for kikuyu, which regrows readily from a fragment left behind.
- Expect several attempts. A single treatment rarely finishes the job. Realistic timelines run to several months and multiple rounds, and professional turf advice generally treats six or seven attempts over roughly a year as a normal outcome, not a failure.
- Patch and thicken the lawn afterwards. A dense, well-fed, correctly mowed lawn resists re-invasion far better than a thin one, so finish with turf or seed matching your main grass and a fertilising program suited to it.
How to Kill Winter Grass in Your Lawn, Including Buffalo
Not sure if what you’re looking at is actually winter grass? Our guide to identifying winter grass covers the boat-shaped leaf tip and clump growth habit that set it apart from a dormant lawn. Winter grass, Poa annua, is a completely different problem from couch, kikuyu and buffalo fighting each other. It’s an annual weed grass rather than a perennial turf species, it germinates once soil temperatures drop to around 16 to 17°C in autumn, and because it’s biologically distinct from the warm-season grasses it’s invading, genuine selective products exist.
| Type | Active Constituent | Timing | Buffalo-Safe? |
|---|---|---|---|
| Pre-emergent | Oxadiazon (e.g. 10 g/kg in a combined fertiliser product) | Mid to late autumn, before germination; label rates around 3–4 kg per 100 m², giving roughly 10 weeks of control | Yes, labelled for established buffalo, couch, kikuyu and zoysia |
| Post-emergent | Endothal 175 g/L (present as the dipotassium salt) | Once winter grass has already emerged | Yes, labelled products name buffalo including Sir Walter, plus couch, bent and browntop |
As with every product in this guide, check the specific label on your own bottle before applying it. Formulations and registrations change, and the rates above are illustrative examples from currently registered labels rather than a universal figure.
How to Kill Couch Grass or Buffalo Grass Completely
Removing an entire lawn, rather than spot-treating a patch of one grass invading another, is a different job with the same toolkit whichever grass you’re getting rid of:
- Glyphosate, sprayed rather than painted, is the fastest chemical option once you’re removing the whole area rather than protecting a neighbouring grass. Apply during active growth, typically spring through autumn, for the best uptake.
- Solarisation covers the area with clear plastic sheeting through the hottest part of summer, using trapped solar heat to kill the grass and much of its root system without chemicals.
- Physical removal with a turf cutter or spade, digging out rhizomes and stolons rather than just scalping the leaf, is the most reliable single method for a smaller area and the only one that works immediately.
- Boiling water scalds and kills small patches without any chemical involved, though it’s slow going and only practical at a small scale.
Whichever method you use, plan to go back over the area at least once more a few weeks later for regrowth from any surviving rhizome, before turfing or seeding the replacement lawn. A home remedy like vinegar and water sometimes gets suggested as a natural herbicide, but it has little real effect on an established root system, so treat it as a myth rather than a genuine option for anything beyond a few young seedlings.
Common Mistakes That Waste a Season
- Spraying a general lawn weed killer and expecting it to touch an unwanted grass species. Broadleaf herbicides were never built for this job and won’t do anything to it.
- Trying an off-label grass-selective product hoping it’ll spare your lawn grass because you’ve read it’s “broadleaf”, when every common lawn grass, buffalo included, is a monocot, not a broadleaf plant.
- Broad-spraying glyphosate across a mixed patch instead of painting it onto the unwanted grass specifically, and losing the good grass along with the bad.
- Giving up after one round. Grass-versus-grass removal is a multi-attempt job by nature, not a sign you’re doing it wrong.
- Letting an invasion sit past the quarter-of-the-lawn mark before acting, at which point spot treatment is no longer a realistic strategy.
When to Call a Pro
Call a turf contractor once an invading grass covers more than about a quarter of the lawn, since that’s usually the point where a professional strip-and-resod job is faster and cheaper overall than continuing to spot-treat. It’s also worth a call if you can’t confidently tell which grasses you’re actually looking at, since every method here depends on knowing exactly what you’re trying to keep and what you’re trying to remove.
This is one of several grass-identity problems worth sorting out before you spray anything; if you’re not sure which grass is which in the first place, start there. Clumpy, fast-growing tufts with a distinctive seed head are a different weed grass again, not couch or kikuyu: see our guide to identifying and removing paspalum [INTERNAL LINK OPPORTUNITY: link to “Paspalum: How to Identify and Remove It From Australian Lawns”, draft 1232, not yet published]. And if the same patch is also carrying bindii, clover or another broadleaf weed, that’s a separate, more straightforward problem with real selective options, covered in the full guide to buffalo-safe weed control.
See the full lawn weeds guide [INTERNAL LINK OPPORTUNITY: link to “Lawn Weeds in Australia: The Complete Guide”, draft 1343, not yet published] for how this fits with every other weed on an Australian lawn.
Frequently Asked Questions
How do I kill couch grass without killing my buffalo lawn?
There’s no selective herbicide for this. Paint or wipe glyphosate directly onto the couch grass’s leaf blades with a brush or gloved hand, lifting runners clear of the buffalo first, and expect to repeat the process several times over a few months.
How do I get rid of couch grass completely?
For removing an entire couch lawn rather than protecting a neighbouring grass, spray glyphosate during active growth, dig out the rhizomes, or solarise the area under clear plastic through summer, then resod or reseed once it’s clear.
How do I kill winter grass in a buffalo lawn?
Winter grass is the one case in this cluster with genuine selective options. Apply an oxadiazon-based pre-emergent in mid to late autumn before it germinates, or a labelled post-emergent product such as one based on endothal if it’s already emerged, checking that your specific product’s label names buffalo grass.
How do I kill buffalo grass if I want to remove it?
The same general toolkit as removing any other established lawn: glyphosate sprayed across the area, solarisation under clear plastic, or physical digging out of the rhizomes and stolons, followed by resodding or reseeding with your grass of choice.
How do I get rid of kikuyu grass invading my buffalo lawn?
The same spot-treatment approach as couch in buffalo: paint glyphosate directly onto the kikuyu rather than spraying, dig out root fragments where you can, and act early, since kikuyu regrows readily from anything left behind and becomes unmanageable once it’s well established.
How do I kill buffalo grass that’s invading a couch lawn?
The direction doesn’t change the method. Spot-paint the buffalo runners with glyphosate, lifting them clear of the couch first, and expect to repeat the process rather than clearing it in one go.
How do I kill clover growing in a buffalo lawn?
Clover is a broadleaf weed rather than a grass, so this is a different and easier problem with real selective options: bromoxynil or MCPA-clopyralid-diflufenican based products are safe on buffalo, unlike dicamba blends. It’s covered in full, including rates and timing, in our guide to getting rid of bindii and clover.
