Lawn care
How to get rid of nutsedge in your lawn
That fast-growing, spiky weed isn’t grass, and that’s exactly why it keeps beating your mower.
You mow the lawn, and two days later there are pale, spiky shoots standing taller than everything around them. That’s nutsedge, and it’s one of the most stubborn weeds a homeowner can face. It looks like grass at a glance, but it isn’t, and that difference is the whole reason it’s so hard to get rid of. The good news: once you understand what nutsedge actually is and use the right product on it, it’s very manageable.
Why nutsedge is so hard to kill
Nutsedge (often called nutgrass) is a sedge, not a grass, you can feel it in the stem: sedges have triangular stems, “sedges have edges.” It grows faster than your turf, especially in warm, wet, poorly drained spots, which is why it shoots up so quickly after mowing. But the real problem is underground: nutsedge spreads through a network of tubers (the “nuts” in the name). Pull the top and you leave the tubers behind, and each one can sprout a new plant. That’s why hand-pulling almost never works, and why the wrong weed killer barely fazes it. To beat nutsedge you need a product that moves into the plant and reaches that tuber system.
The product for the job
Sulfentrazone 4F
A selective herbicide (39.6% Sulfentrazone) built specifically for the weeds most products can’t touch, especially nutsedge and kyllinga. It works both ways: as a pre-emergent that stops sedges before they establish, and as a post-emergent on nutsedge that’s already up. Because it’s soil-active and taken up by the plant, it reaches the tuber system rather than just burning the tops.
Controls yellow AND purple nutsedge · safe on labeled lawns
Yellow vs. purple nutsedge (it matters)
There are two common types, and they don’t behave the same. Yellow nutsedge is the more common and the easier of the two to control, often a single well-timed application does it. Purple nutsedge is tougher: the label specifically recommends split applications for it, an initial treatment followed by a second one once you see active regrowth, spaced about 35 days apart. If you’re not sure which you have, treating on the split-application schedule is the safer bet for lasting control.
How to apply it
Timing and technique make the difference between knocking nutsedge back and actually clearing it:
Treat when it’s young and actively growing. Nutsedge is far easier to control early, before it matures and forms new tubers, than once it’s well established.
Water it in. Sulfentrazone 4F needs about half an inch to an inch of irrigation or rainfall after application to activate. If it stays dry for 7 to 10 days, control drops off.
Split the application for purple nutsedge. One treatment, then a second when regrowth appears, about 35 days later.
Don’t exceed the yearly limit. The label caps total use at 12 fluid ounces per acre per twelve-month period, so don’t over-apply.
A few important label rules
Only apply Sulfentrazone 4F to an established lawn, wait until after the second mowing of new turf, and confirm your grass type is on the label’s tolerant list before spraying. Don’t apply it to ornamental beds, or to areas with flower bulbs or non-woody perennials, since it’s soil-active and can damage them as they come up. And keep it off golf-style putting greens. As always, follow the label rate and keep people and pets off the treated area until it’s dry.
Keep it from coming back
Nutsedge loves moisture and thin turf, so the best long-term defense is cultural: fix drainage in soggy spots, avoid overwatering, and keep your lawn thick and healthy so sedge has less room to establish. A dense lawn plus a well-timed treatment on any sedge that does appear is what keeps it gone for good.
Common questions
Is nutsedge a grass or a weed?
It’s a sedge, a distinct plant family, not a true grass, even though it looks grass-like. You can tell by the stem: sedges have a triangular, edged stem, while grass stems are round. That difference is why regular lawn weed killers often don’t work on it, and why a sedge-specific product is needed.
Why does nutsedge come back after I pull it?
Because it spreads by underground tubers, the “nuts” it’s named for. Pulling removes the shoot but leaves the tubers behind, and each one can grow a new plant. A herbicide that moves into the plant and reaches the tuber system, rather than just killing the top, is what actually stops the cycle.
Will Sulfentrazone 4F hurt my lawn?
Not when it’s used on a labeled, established turf type at the correct rate, the label lists tolerant cool- and warm-season grasses, including St. Augustine and centipede at the appropriate rates. Confirm your grass type is on that list, wait until new turf has been mowed at least twice, and follow the label rate. Avoid applying to ornamental beds or areas with flower bulbs.
How long does it take to kill nutsedge?
You’ll usually see the nutsedge decline over a couple of weeks after a properly activated application. Yellow nutsedge often responds to a single treatment; purple nutsedge typically needs a second application about 35 days after the first to fully control the tuber system.
Do I need to water after applying?
Yes. Sulfentrazone 4F is soil-activated and needs about half an inch to an inch of irrigation or rainfall to work. If no moisture arrives within 7 to 10 days of application, control will be reduced.
Can I stop nutsedge before it appears?
To a degree, yes. Sulfentrazone 4F has pre-emergent activity, so it can suppress sedges before they establish, and keeping your lawn thick and well-drained removes the wet, thin conditions nutsedge favors. Prevention plus a timely treatment on any that appears is the most reliable approach.
Ready to clear the nutsedge for good?
Contact Agrisel to find a reseller carrying Sulfentrazone 4F for your lawn.