Dollarweed in a Wet Lawn: Why It Takes Over and What Kills It Without Killing the Grass
- Dollarweed, also called pennywort, is a perennial weed that LSU AgCenter says grows mostly in lawn areas with moist or wet soil.
- Its round, shiny leaves attach to the stem at the center of the underside, which is the easiest way to identify it.
- It spreads by seed and by underground rhizomes that link several leaves together, so pulling the leaves alone rarely works.
- LSU AgCenter names metsulfuron as the most effective herbicide on dollarweed, and repeated applications may be needed.
- Improving drainage is often the long-term fix, because a wet lawn will keep growing dollarweed.
- How to identify dollarweed
- Why dollarweed thrives in New Orleans yards
- Why pulling the leaves isn't enough
- What kills dollarweed without killing the grass
- The long-term fix is drainage
- Keep the lawn thick enough to crowd it out
- Dollarweed through the year
- When it's worth calling someone
- Frequently asked questions
It starts as a few shiny, round leaves near the downspout. By midsummer there’s a bright green carpet of them in every low spot, standing a little taller than the St. Augustine around it. Dollarweed is one of the easiest lawn weeds to recognize and one of the most stubborn to remove, because it’s telling you something about the soil underneath.
At TurnKey Lawn Care, weed control is part of the lawn care we provide across the metro. If dollarweed has taken over a corner of the yard, request a free estimate and we’ll look at the weed and the wet ground feeding it.
This guide covers how to identify dollarweed, why it thrives in so many New Orleans yards, how to pull it properly, how herbicides fit in, and the drainage fixes that stop it coming back.
How to identify dollarweed
The LSU AgCenter home lawn series describes dollarweed as having shiny, silver-dollar-shaped, bright-green leaves with wavy edges. The detail that settles it is underneath: each leaf’s stem attaches at the center of the underside, like an umbrella handle. In late spring and summer it also sends up flower stalks. LSU describes tiny white flowers clustered at the top of those stalks. Features to check when you find a round-leaved weed in the lawn:
- A leaf roughly the size and shape of a coin, bright green and glossy on top
- Gently wavy edges rather than deep lobes or scallops
- The stem joined to the middle of the leaf’s underside, not to its edge
- Several leaves connected to one another under the soil when you dig
- Growth concentrated in low, wet or frequently watered parts of the yard
That last point matters as much as the leaf shape. If round leaves are spread evenly across a dry lawn, it may be a different weed. If they’re packed into the soggy areas, it’s almost certainly dollarweed.
Why dollarweed thrives in New Orleans yards
LSU calls dollarweed a moisture-loving weed and notes it’s typically found in lawn areas with moist or wet soil. Few places offer more of that than a low-lying New Orleans yard after a wet spring. Several common conditions around the metro feed it:
- Low spots and heavy soil that stay wet for days after a storm
- Downspouts and AC condensate lines that drain onto the lawn
- Irrigation timers set to run often in a season when rain is already doing the work
- Thin turf that leaves bare soil for the weed to colonize
Overwatering deserves its own mention. A sprinkler system running every day during a rainy stretch creates the permanently damp surface dollarweed prefers. Our Louisiana lawn watering schedule covers how to count rain toward the week’s total.
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Why pulling the leaves isn't enough
LSU explains that dollarweed spreads by seed and by rhizomes, which are underground stems. Those rhizomes can form underground chains that connect several of the leaves you see above ground. Pull a leaf and the rhizome stays in the soil, ready to send up another one. That’s why a patch that was hand-weeded in May can look untouched by July. LSU’s advice is to dig up the rhizomes when you physically remove dollarweed. In a small patch, that’s realistic:
- Wait for moist, not saturated, soil. The rhizomes come out more completely when the ground is soft but not muddy.
- Loosen the soil around the patch. Use a hand fork or trowel to lift the soil gently rather than yanking the leaves.
- Follow the chains. Trace the rhizome from leaf to leaf and lift as much of it as you can in one piece.
- Bag it, don’t compost it. Pieces of rhizome left in a compost pile or on the lawn can root again.
- Fix the wet spot. Redirect the downspout or adjust the sprinkler zone before the patch refills.
For a large area laced through St. Augustine, hand-digging becomes impractical. That’s where herbicides and drainage work come in.
What kills dollarweed without killing the grass
LSU AgCenter states that metsulfuron is the most effective herbicide on dollarweed. It also notes that repeated applications may be necessary to achieve control, and that applications should be made in late spring when dollarweed is observed. The phrase “without killing the grass” depends entirely on the product and your turf type. Lawn herbicides are labeled for specific grasses, and a product that’s safe on one warm-season grass can injure another. Always confirm the label lists St. Augustine, centipede, zoysia or Bermuda before you apply anything, and follow the manufacturer’s directions exactly, as LSU stresses. A few practical points make herbicide work more effective:
- Treat when the weed is actively growing and visible, rather than after it has been mowed down to stubs
- Expect to repeat, since a single application rarely clears established rhizomes
- Correct the wet conditions at the same time, or new seedlings and rhizome shoots will fill the gaps
- Avoid stressing the lawn with other treatments in the same week
Our pages on post-emergent weed treatment and weed control for New Orleans lawns cover how we time and apply weed treatments on local lawns.
The long-term fix is drainage
LSU puts it plainly: improving drainage may be necessary for long-term control. Herbicide can clear a patch, but if the ground stays wet, dollarweed will return to it. Depending on the yard, drainage improvements can be small or substantial:
| Situation | Typical fix | Scale of work |
|---|---|---|
| Downspout empties onto the lawn | Extend or redirect it to a bed, drain or the street | Small |
| Sprinkler zone overwatering one area | Adjust run time or head direction, or cap a head | Small |
| Compacted soil that ponds after rain | Core aeration when the grass is actively growing | Moderate |
| A true low spot that holds water for days | Regrading, a French drain or a drainage bed | Larger project |
Our drainage solutions for wet yards page covers the bigger fixes, from regrading to installed drains.
Keep the lawn thick enough to crowd it out
LSU recommends maintaining a healthy lawn through regular mowing, proper fertilization and attention to soil pH. A dense stand of St. Augustine leaves less bare soil for dollarweed to claim. Mowing at the right height for your grass, feeding according to a soil test rather than by habit, and repairing thin areas promptly all make the lawn more competitive. It’s slower than spraying, but it’s what keeps the weed from coming straight back. Our guide on proper mowing height for Gulf Coast grasses gives the heights for St. Augustine, Bermuda, zoysia and centipede. Mowing a little higher on a wet-prone lawn keeps the canopy thick, which shades the soil surface and makes it harder for new dollarweed seedlings to get going.
Dollarweed through the year
Dollarweed is a perennial, so the same plants and rhizomes carry over from one season to the next. What changes through the year is how visible it is and how easy it is to deal with. In a typical New Orleans yard the pattern runs roughly like this:
- Late winter: leaves are sparse, which makes it a good time to map where the wet spots are and plan drainage work before spring
- Spring: growth picks up with warmth and rain, and LSU’s guidance to treat in late spring when dollarweed is observed applies here
- Summer: patches expand fastest in low areas that stay wet after afternoon storms, and flower stalks appear
- Fall: growth slows, and it’s a sensible time to thicken the surrounding turf so bare soil doesn’t invite new plants next year
The takeaway for planning is that drainage work and turf repair can happen in the quieter months, while herbicide work belongs to the period when the weed is up and growing.
When it's worth calling someone
A few leaves near a downspout are a weekend job. A lawn where dollarweed has filled every low area is a different project, and spraying the same patch again and again without fixing the water rarely works. It’s usually worth getting help when:
- The weed covers a large share of the lawn and is woven through the St. Augustine rather than sitting in one patch
- Water stands in the same areas for a day or more after rain, which points to a grading or drainage problem
- You aren’t sure which herbicides are safe on your grass type, or you’ve already had a product damage the lawn
- The lawn is thin and patchy, so removing the weed would leave bare soil behind
In those cases the fix is a plan that covers the weed, the water and the turf together. Treating one without the others is how dollarweed ends up as a permanent feature of a yard.
Frequently asked questions
What kills dollarweed but not grass?
LSU AgCenter names metsulfuron as the most effective herbicide on dollarweed, applied in late spring when the weed is visible and repeated if needed. Whether a product is safe on your lawn depends on the label, so confirm it lists your grass type before applying.
How do I get rid of dollarweed?
Dig out small patches along with the underground rhizomes, treat larger areas with a herbicide labeled for dollarweed and your grass type, and fix the wet conditions that let it thrive. LSU AgCenter notes that improving drainage may be necessary for long-term control.
Why do I have so much dollarweed in my yard?
Dollarweed is a moisture-loving weed that grows in lawn areas with moist or wet soil. Low spots, downspouts draining onto the grass and sprinklers that run during rainy weather all create the conditions it prefers.
Is dollar weed the same as creeping Charlie?
They’re different weeds. Dollarweed’s round, glossy leaf is attached to its stem at the center of the underside, which LSU AgCenter uses as its key identifying feature, and that center attachment is the quickest way to tell it apart from other creeping lawn weeds.
Get the wet spot and the weed sorted together
Show us where the dollarweed is thickest and where water sits after rain. We’ll recommend the treatment and the drainage fix together and give you a free estimate, with the price agreed before any work starts.
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