What Kills Dollar Weed? | Three Working Methods That Actually Stop It

Dollarweed is killed most reliably by selective herbicides containing metsulfuron-methyl, atrazine on St. Augustine and Centipede lawns, or 2,4-D mixtures — but the underlying cause is wet soil, and fixing drainage is what keeps it gone for good.

That penny-sized leaf with the scalloped edge popping up in your lawn is a moisture signal, not just a weed problem. Dollarweed thrives where the ground stays damp and compacted. Spraying without changing the watering habit is like mopping with the faucet running. The real fix starts with how you water, then hits the weed with the right chemistry for your grass type.

Most dollarweed killers either attack the plant through its leaves or prevent new sprouts from emerging. Your grass type decides which one is safe to use, and your watering schedule decides whether the problem comes back next season.

What Type of Lawn Are You Treating? The Chemical Pick Depends On It

The single most common mistake is buying a dollarweed killer that damages your own grass. The herbicide that works beautifully on St. Augustine will kill Bermuda, and the one labeled “broadleaf killer” might not touch dollarweed at all.

Step One: Starve It Before You Poison It

Dollarweed loves soil that stays damp from frequent light watering. The weed’s underground rhizomes run through the top few inches of wet ground, and each node can send up a new plant. Cutting water back stresses the weed and makes herbicides more effective.

Reduce total weekly water — including rainfall — to no more than one inch. Switch from three or four short watering sessions per week to two deeper ones. A 45-minute zone soak, twice a week, reaches deeper roots and leaves the surface dry enough to discourage dollarweed germination. If you have low spots that hold puddles, level them or install a French drain in the worst area. Compacted soil holds water at the surface; aerating in spring opens channels for it to drain.

Let the lawn dry out for about two weeks before you spray. Stressed dollarweed takes up herbicide more readily than a plant sitting in saturated ground.

Step Two: Post-Emergent Spraying — Timing and Chemistry

Apply herbicides in late spring or early summer when dollarweed is actively growing and soil temperatures are between 70°F and 85°F. Spray on a calm day with no rain forecast for 24 hours.

Metsulfuron-Methyl (The Most Targeted Option)

Products like Martin’s Top Shot, MSM Turf, and Manor are selective and safe for St. Augustine, Bermuda, Zoysia, and Centipede. Mix one ampoule of Top Shot per gallon of water, shake well, and apply with a pump sprayer at low pressure using a fine fan nozzle. Coverage should wet the leaves but not drip off. The plant yellows over a couple of weeks and dies within three to four weeks. Expect St. Augustine to slow its growth for about three weeks afterward — that is normal and temporary. Reapply every seven to ten days if new dollarweed appears.

Atrazine (St. Augustine and Centipede Only)

Atrazine is effective on dollarweed in St. Augustine and Centipede lawns but it damages Bermuda. An important caveat: the EPA has restricted atrazine for homeowner use in some regions because of groundwater concerns. Check local regulations before buying. Products like Hi-Yield Atrazine Weed Killer and Southern Ag Atrazine St. Augustine Weed Killer are labeled for post-emergent use on actively growing weeds in warm weather, or as a pre-emergent in early spring when soil temperatures hit 55°F to 60°F.

2,4-D Mixtures (Bermuda and Zoysia)

SpeedZone Broadleaf Herbicide (2,4-D plus MCPP and dicamba) is safe for Bermuda and Zoysia. Trimec Southern is formulated for St. Augustine at a 1 oz per gallon rate — using the SpeedZone rate on St. Augustine can burn it. For other grasses, the Trimec rate is 2 oz per gallon. Mix half the water in the tank, add the product, add the remaining water, and shake.

Non-Selective Spot Treatment (Isolated Patches)

For small clumps where you do not mind killing the surrounding grass, paint glyphosate (Roundup) onto individual dollarweed leaves with a foam brush, or spray carefully with a handheld bottle. This method works fast but leaves bare spots you will need to reseed or plug.

Where to Find a Ready Product Roundup

If you want to skip comparing labels and grab a pre-tested product matched to your grass type, we have a tested list of the best dollar weed killers with mixing instructions and grass-compatibility notes.

Step Three: Manual Removal for Small Infestations

If you have a few plants in a garden bed or a small patch near the driveway, hand-pulling works as long as you get every piece of the root system. Wait until the soil is moist but not soaking. Use a weeding tool to loosen the ground around the root crown, then pull straight up and check that all the white, stringy rhizomes came out. Bag the pulled plants in a black trash bag and leave it in the sun for a few days before tossing — dollarweed can reroot from stem fragments left on the soil surface.

Preventing Dollarweed From Coming Back

Once the dollarweed dies, you have a window before it returns. Fill bare spots with overseeding or plugs so dollarweed seeds cannot find open soil. Apply a slow-release fertilizer like Lawnifi Foundation to push thick grass growth that shades the ground — dollarweed seeds need light to germinate. If you had the problem in a low wet area, improve drainage before next spring. And keep watering deep and infrequent: one inch per week, split into two sessions, is the maintenance number that keeps most broadleaf weeds from getting comfortable.