Spraying random weed killer on your lawn is like taking antibiotics for a broken bone. You need to know what you’re dealing with before you can fix it.

Lawn weeds fall into two categories, and the treatment for each is completely different. Misidentify the weed, and you waste money, time, and possibly damage your grass.

Broadleaf vs Grassy Weeds

This is the first question you need to answer when you see a weed.

Broadleaf weeds have wide, flat leaves with visible veins that branch out. Think dandelions, clover, and chickweed. They look obviously different from grass.

Grassy weeds look like grass — because they are grass. Just the wrong kind. Crabgrass, goosegrass, and annual bluegrass blend in until they take over. They’re harder to spot early and harder to treat selectively.

Why does this matter? Because broadleaf herbicides won’t kill grassy weeds, and grassy weed killers won’t touch broadleaf weeds. Using the wrong product does nothing except waste your money.

The 10 Most Common Lawn Weeds

Broadleaf Weeds

1. Dandelion — The one everyone recognizes. Yellow flower, puffy seed head, deep taproot. Perennial, meaning it comes back from the root every year. Hand-pulling works if you get the entire taproot (use a dandelion puller tool). For widespread infestations, a broadleaf herbicide with 2,4-D handles them.

2. White Clover — Low-growing, three-leafed (sometimes four if you’re lucky), white flower clusters. Actually fixes nitrogen in the soil, which is why some people leave it. If you want it gone, a broadleaf herbicide containing triclopyr works best.

3. Chickweed — Small, bright green leaves with tiny white flowers. Thrives in cool, moist conditions — spring and fall. It’s an annual, so pre-emergent in early spring prevents it. Post-emergent broadleaf sprays kill existing plants.

4. Henbit — Square stems, scalloped leaves, purple flowers. Common in early spring across the South and Midwest. Another annual that pre-emergents handle well. Often confused with purple deadnettle (similar treatment for both).

5. Dollarweed (Pennywort) — Round, silver-dollar-shaped leaves on a single stem. Loves wet soil — if you have dollarweed, you’re probably overwatering. Fix the moisture problem first, then spot-treat with a broadleaf herbicide.

6. Spurge — Low, mat-forming weed that hugs the ground. Leaves are small with a reddish spot in the center. Bleeds milky sap when broken. Thrives in hot, dry conditions and thin turf. Pre-emergent in spring is the best defense; post-emergent sprays work on young plants.

Grassy Weeds

7. Crabgrass — The big one. Light green, spreads flat in a star pattern, thrives in summer heat. Annual — it dies with the first frost but drops thousands of seeds first. Pre-emergent herbicide in early spring is the only reliable control. Once it’s established, post-emergent options (quinclorac) exist but are less effective than prevention.

8. Nutsedge (Nutgrass) — Looks like grass but grows faster, taller, and has a distinctive V-shaped or triangular stem. It’s actually a sedge, not a grass. Extremely tough to kill. Regular broadleaf or grassy weed herbicides won’t work — you need a product specifically labeled for nutsedge (sulfentrazone or halosulfuron). Thrives in wet soil.

9. Goosegrass — Similar to crabgrass but darker green, with a flattened, whitish center. Loves compacted soil — you’ll see it along sidewalks, driveways, and high-traffic paths. Pre-emergent timing is the same as crabgrass.

10. Annual Bluegrass (Poa annua) — Light green, fine-textured, produces seed heads even when mowed short. Dies in summer heat. Most visible in spring when it sticks out as lighter patches in your lawn. Pre-emergent in fall prevents spring germination.

Pre-Emergent vs Post-Emergent Strategy

Pre-emergent herbicides create a chemical barrier in the top layer of soil that prevents weed seeds from germinating. They don’t kill existing weeds — they stop new ones from sprouting.

Timing is everything:

  • Spring application — When soil temperatures hit 55°F for several consecutive days. This targets crabgrass, goosegrass, and summer annuals. Too early and it breaks down before the weeds germinate. Too late and you missed the window.
  • Fall application — Targets henbit, chickweed, and annual bluegrass that germinate in autumn.

Post-emergent herbicides kill weeds that are already growing. They come in two forms:

  • Selective — Kills specific weeds without harming your grass. This is what you want for lawn use. Always check that the product is safe for your grass type.
  • Non-selective — Kills everything it touches (glyphosate is the most common). Only use for spot-treating in cracks, edges, or areas you plan to reseed.

When to Spray vs Pull

Pull when:

  • You have a small number of weeds (under a dozen)
  • The weed has a taproot you can extract completely (dandelion)
  • You’re near garden beds, trees, or areas where spray could drift
  • The weed is in a newly seeded area where herbicides could damage young grass

Spray when:

  • Weeds are widespread across the lawn
  • You’re dealing with mat-forming weeds (spurge, crabgrass) that are impractical to pull
  • The weed regrows from root fragments when pulled (nutsedge)
  • You have a recurrent annual weed problem (pre-emergent is the answer)

The Bigger Picture

Weeds are a symptom, not the disease. A thick, healthy lawn crowds out weeds naturally. If you’re fighting weeds constantly, look at the underlying issues:

  • Thin turf — Overseed in fall to thicken the stand
  • Compacted soil — Aerate annually
  • Wrong pH — Get a soil test and correct it
  • Mowing too short — Raise the deck to 3–3.5 inches
  • Overwatering — Dollarweed and nutsedge are telling you something

Kill the weeds you have. Prevent the ones you don’t. And build a lawn that fights them for you.

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