Types of weeds in grass: grassy, broadleaf and sedges
How to tell grassy weeds, broadleaf weeds and sedges apart in a lawn, with examples like crabgrass, dandelion and nutsedge and what each group needs, from university extension sources.
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Short answer
Lawn weeds fall into three groups: grassy weeds with narrow blades like crabgrass, broadleaf weeds with wide leaves like dandelion and dollarweed, and sedges, which look like grass but have triangular stems. Each group needs a different response, and university extension services say the first step for all of them is a thick, healthy lawn. Name the group before you buy any product.
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A weed guide and a pen are enough if your lawn has a few weeds and you only need to name them.
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Lawnzo helps when you want weeding, mowing and feeding set on the right days for your grass and the weather, with a journal of what you did and photos.
At a glance
| Feature | Grassy weeds | Broadleaf weeds |
|---|---|---|
| Looks like | Narrow blades, often coarser or lighter green than the lawn | Wide leaves: a rosette for dandelion, one round leaf per stalk for dollarweed |
| Examples | Crabgrass, quackgrass, tall fescue in bluegrass, sandbur | Dandelion, dollarweed |
| Life cycle | Crabgrass is an annual; quackgrass is a perennial | Dandelion is a short-lived perennial |
| How it spreads | Thousands of seeds, or creeping underground stems called rhizomes | Wind-borne seeds and taproot pieces; dollarweed by rhizomes |
| First fix | A thick stand of grass with no bare soil | Vigorous turf, and correct overwatering for dollarweed |
| Selective killers | Rarely available for perennial grass weeds | Broadleaf killers such as 2,4-D and MCPP, which also harm many other plants |
Three groups and how to tell them apart
The easiest test is the stem and the leaf. Grasses have narrow leaves with nodes along the stem. Sedges, according to University of Florida (UF/IFAS) Extension, usually have triangular, solid stems and leaves often arranged in threes, and the rhyme botany students use says “Sedges have edges, and rushes are round, but grasses have nodes from their tips to the ground.” Broadleaf weeds are every other plant that is not grass-like, from dandelions to clover. Penn State Extension gives the same first step for Pennsylvania lawns: tell broadleaf from grass weeds, because broadleaf weeds have wider leaves with a net of veins, while grass weeds have long, narrow leaves with parallel veins. It also describes yellow nutsedge as a sedge with triangular stems that likes moist or wet spots.
Our tip: roll a stem between your finger and thumb. A three-sided stem points to a sedge, which needs a different plan from a grassy weed. It also helps to know when the plant appears: Wisconsin extension says perennial grasses are already green in early spring, while annual grasses such as crabgrass do not show until late spring or early summer and die off quickly in fall.
Grassy weeds: crabgrass, quackgrass and look-alikes
Crabgrass is a warm-season annual. University of Wisconsin Extension describes lighter green, coarse patches among the lawn, with finger-like or fork-like seedheads that make enormous amounts of seed. It thrives in full sun, bare soil and thin turf, and seed germinates when soil warms into the upper 50s to low 60s Fahrenheit for several days. The same source says forsythia bloom often comes before germination and can serve as a timing cue for a pre-emergent herbicide.
Perennial grasses are harder. UW Extension says control options are limited because the weeds are so close to the lawn grasses, and that tall fescue, creeping bentgrass, zoysiagrass, quackgrass and nimblewill all turn up as weeds in bluegrass lawns. Quackgrass has coarse, wide leaves and creeping rhizomes. Tall fescue grows in clumps and looks coarser than bluegrass. In the South, UF/IFAS lists southern sandbur, with spiny seedheads that cling to shoes and skin, and wavyleaf basketgrass in shady areas.
Broadleaf weeds: dandelion, dollarweed and clover
Dandelion has lance-shaped leaves in a rosette, smooth hollow flower stalks, milky sap and a taproot that UW Extension says is usually 6 to 12 inches long and can reach 3 feet. Plants regrow from root pieces, particularly the top half, so a digging tool that lifts 2 to 3 inches of root or more works better than snapping the leaves.
Dollarweed, also called pennywort, has one round leaf per stalk, up to the size of a silver dollar, and looks like a lily pad. UF/IFAS says it shows up where a lawn is overwatered or naturally wet, and that hand-pulling works if you get the white rhizomes too. UF also says clovers often indicate soil with low nitrogen, and that broadleaf plantain prefers high-pH soil.
Sedges: nutsedge and its tubers
Yellow and purple nutsedge are the most common sedge weeds in turf, UF/IFAS says. They spread by underground runners and tubers, and the tubers are why they are so hard to remove. Despite their flowers, sedges seldom reproduce by seed, so the runners and tubers are what you are fighting.
Sedges thrive where the turf is struggling, in areas that stay wet, in compacted soil and in high-traffic spots. UF/IFAS says to correct the cause of continuously wet ground first. Hand-pulling can work for a few plants if you remove all the runners and tubers. Mulch and landscape cloth do not stop them, and chemical control can need repeated applications for several years.
Read the weed as a clue to the lawn
UF/IFAS says each weed prefers its own conditions. Annual bluegrass and chickweed are winter weeds that point to a lawn mown too low. Goosegrass thrives in compacted, wet soil. Sedges, doveweed, dollarweed and eclipta all like soggy ground, which may mean overwatering, an irrigation leak or poor drainage. Those details come from Florida and apply most to the South, so check your own region with your county Extension office.
Crabgrass shows the same lesson in the North: UW Extension says the biggest outbreaks are in thin lawns in full sun, and that if it comes back every year, the site conditions and your care need review. In every case, the weed is a symptom, so fixing the lawn removes the reason it grew there.
Where to start with control
These are the sources' common points. Keep the lawn thick, mow at the height recommended for your grass and never remove more than a third of the blade at once, feed and water correctly, and fill bare patches. UW Extension says dandelions are generally only a problem in lawns not growing vigorously enough to outcompete them, and that late summer and early fall is the best time to treat them with herbicide.
If you use an herbicide, read the label first. UF/IFAS puts it plainly: the label is the law, and products are safe and effective only if you follow all the instructions. UW Extension notes that broadleaf killers harm many plants, not just weeds, and that selective products are rarely an option against perennial grass weeds, so naming the group first decides what is even possible. Get an extension office or a nursery to confirm an identification you are unsure about.
Frequently asked questions
What are the three main types of lawn weeds?
Grassy weeds with narrow blades, such as crabgrass; broadleaf weeds with wide leaves, such as dandelion; and sedges, which have triangular stems.
How do I tell crabgrass from regular grass?
Crabgrass forms lighter green, coarse patches with finger-like seedheads in summer, and as an annual it dies off in fall.
How do I tell a sedge from a grass?
Sedges have triangular, solid stems, and grasses have nodes along the stem. Roll the stem between your fingers to feel the edges.
Why do weeds keep coming back in my lawn?
Often the lawn is thin, mown too low, overwatered or compacted. Extension sources say healthy, thick turf is the best long-term defense.
Does Lawnzo identify weeds?
No. Lawnzo plans mowing, watering, feeding and weeding for your grass and the weather.
Our pick
Lawnzo, to fix the lawn that keeps the weeds out
Once you know what is growing, the work is timing. Lawnzo builds a seasonal plan from your grass, sun and watering, checks each task against the forecast, and shows the reason when it keeps, delays or skips a job. Log what you used and add photos to compare a patch week by week.
- Mowing height and cadence for your grass, with the one-third rule
- Tasks kept, delayed or skipped by the weather, with the reason shown
- A journal with products, quantities, costs and photos
Sources · checked October 1, 2026
- UF/IFAS Gardening Solutions: Weedy grasses
- UF/IFAS Gardening Solutions: Sedges
- UF/IFAS Gardening Solutions: Dollarweed
- UF/IFAS Gardening Solutions: Reading the weeds
- Penn State Extension: Weed Management in Turf (last updated 2006)
- UW-Madison Extension Horticulture: Crabgrass
- UW-Madison Extension Horticulture: Perennial grass weeds in lawns
- UW-Madison Extension Horticulture: Dandelion
