Common Lawn Weeds: 20-Weed ID Chart, What Each Signals, When to Act

Key takeaways

• Lawn weeds sort into broadleaf weeds (net-veined leaves), grassy weeds (hollow round stems with nodes) and sedges (solid, triangular stems you can roll between your fingers), per UF/IFAS ENH884, rev. December 2024. The group decides which herbicide can work.
• Life cycle sets the calendar: summer annuals such as crabgrass and goosegrass sprout in spring, winter annuals such as annual bluegrass, chickweed and henbit sprout in late summer and fall, and perennials regrow from taproots, rhizomes, stolons or tubers (UGA Bulletin 978, reviewed July 2024).
• Fall is the main window for perennial broadleaf weeds: Purdue and Illinois name mid-September to early November for a broadleaf herbicide, sprayed at 50 to 85°F (Purdue AY-9).
• Several weeds point to a fixable site problem: UC IPM ties annual bluegrass, goosegrass and dallisgrass to overwatering and compacted soil, and black medic and white clover to low nitrogen (UC IPM Pest Notes 74113).
• Weeds are weak pH gauges. Cornell’s weed profile reports dandelion grew 45 percent more fresh weight at soil pH 7.1 than at 6.2 (Cornell Weed Science), the opposite of the acid-soil claim in some popular lawn guides; a soil test settles pH.

What are the most common lawn weeds?

The 20 weeds below all appear on the lawn-weed lists of the land-grant extension services we compiled, from Maryland to UC IPM and UF/IFAS: 14 broadleaf weeds, 5 grassy weeds and 1 sedge. Each row gives the field marks that separate the weed from its look-alikes, the season it shows, and the source page. Crabgrass, which Penn State calls the most common grass weed of Pennsylvania turf, has its own page.

Swipe the table sideways to see every column.

Weed	Type	Life cycle	How to tell it apart	When you see it	Source
Dandelion (Taraxacum officinale)	Broadleaf	Perennial	Basal rosette of toothed leaves 2 to 14 in. long; milky sap; yellow heads on leafless hollow stalks; taproot mostly in the top 6 to 18 in.	Flowers first in spring, then sporadically; seeds sprout all season once soil is at least 50°F	UC IPM; UMD; Purdue
White clover (Trifolium repens)	Broadleaf	Perennial	Three oval leaflets 1/4 to 3/4 in. with a pale inverted-V watermark; creeping stems root at nodes; white globe flowers 1/2 to 3/4 in.	Flowers spring to fall, peak late spring to early summer	Penn State; NC State
Broadleaf and buckhorn plantain (Plantago major, P. lanceolata)	Broadleaf	Perennial	Rosettes with veins running parallel to the leaf edge; broadleaf: oval blades 2 to 7 in.; buckhorn: narrow blades 3 to 12 in., woolly tan crown	Flowers May to August or September	UC IPM; NC State
Ground ivy (creeping Charlie) (Glechoma hederacea)	Broadleaf	Perennial	Square stems that root at the nodes; opposite, scalloped, kidney-shaped leaves 0.5 to 1.5 in.; minty smell when crushed	Blue-purple flowers April and May	UMD; Penn State
Wild violet (Viola spp.)	Broadleaf	Perennial	Glossy, hairless heart-shaped leaves up to 3.5 in.; rhizomes about the size of a little finger; 5-petal flowers 1/2 to 3/4 in.	Flowers April and May	Penn State; Purdue
Yellow woodsorrel (oxalis) (Oxalis stricta)	Broadleaf	Perennial or annual	Three heart-shaped leaflets 1/4 to 1/2 in. that fold at night; 5-petal yellow flowers; upright capsules that fling seed several feet	Flowers and seeds late spring to early fall	Penn State
Virginia buttonweed (Diodia virginiana)	Broadleaf	Perennial	Opposite, stalkless, slightly thick leaves with rough edges, often mottled yellow by a virus; white 4-petal star-shaped flowers; ridged, hairy fruit	Grows spring through summer; flowers summer and fall	UGA B1397; LSU AgCenter; NC State
Dollarweed (pennywort) (Hydrocotyle spp.)	Broadleaf	Perennial	Round, shiny, scalloped leaves up to silver-dollar size with the stalk joined at the center like an umbrella; one leaf per stalk; white rhizomes	Hydrocotyle umbellata flowers April to October (NC State)	UF/IFAS; UF/IFAS EP634; NC State
Common chickweed (Stellaria media)	Broadleaf	Winter annual	Opposite, smooth-edged pointed leaves 1/2 to 1 in.; stems with a line of hairs; tiny white flowers whose 5 split petals look like 10	Sprouts in fall at about 55 to 65°F, flowers in spring	UMD; Penn State
Henbit (Lamium amplexicaule)	Broadleaf	Winter annual	Square stems; scalloped rounded leaves, the upper ones clasping the stem with no stalk; pink-purple tubular flowers 1/2 to 3/4 in.	Sprouts in early fall or early spring; flowers in spring	UMD; NC State
Purple deadnettle (Lamium purpureum)	Broadleaf	Winter annual	Square stems; fuzzy, triangular leaves tinged red or purple and crowded at the top; upper leaves have short stalks, unlike henbit	Sprouts in fall; most visible in April	Penn State; NC State
Spotted (prostrate) spurge (Euphorbia maculata)	Broadleaf	Summer annual	Flat mat from one taproot that does not root at nodes; milky sap; leaves 1/2 to 3/4 in. often with a purple blotch	Emerges early to mid-summer; can flower 3 to 4 weeks later	Penn State; NC State
Black medic (Medicago lupulina)	Broadleaf	Summer annual	Three oval leaflets 1/2 to 3/4 in.; the middle leaflet sits on its own short stalk, unlike clover; yellow flower clusters 1/4 to 1/2 in. that turn into black pods	Sprouts in spring; flowers late spring to early fall	Penn State; UMD
Common lespedeza (Kummerowia striata)	Broadleaf	Summer annual	Small oval leaflets in threes with fine parallel veins angled off the midvein; wiry, prostrate stems with downward-pointing hairs; tiny pink-purple flowers	Emerges late spring to early summer; blooms late summer	LSU AgCenter; UMD; NC State
Annual bluegrass (Poa annua) (Poa annua)	Grassy weed	Winter annual	Light green, boat-shaped leaf tips; crinkled blades 1 to 3 in.; membranous ligule 1 to 3 mm, no auricles; whitish seedheads even when mowed low	Sprouts late summer and fall as soil drops below 70°F; seedheads in spring	UC IPM; NC State
Goosegrass (Eleusine indica)	Grassy weed	Summer annual	Flat rosette with a white to silver flattened center; jagged ligule 1 to 1.5 mm, no auricles; zipper-like seedhead of 2 to 7 spikes; does not root at nodes	Sprouts 3 to 4 weeks after crabgrass, at 60 to 65°F soil; seedheads July to September	Penn State; NC State
Dallisgrass (Paspalum dilatatum)	Grassy weed	Perennial	Clumps of coarse gray-green blades 1/4 to 1/2 in. wide; ligule about 1/4 in., no auricles; short rhizomes with ring-like joints; 2 to 10 drooping seedhead branches	Seeds sprout at 60 to 65°F soil in spring and summer	UC IPM; LSU AgCenter
Quackgrass (Elymus repens)	Grassy weed	Perennial	Long, slender claw-like auricles that clasp the stem; ligule only 1/32 in.; long white rhizomes with sharp tips	Grows in spring and fall; seedheads late May to September	Illinois Extension; UW-Madison
Nimblewill (Muhlenbergia schreberi)	Grassy weed	Perennial	Short blue-green blades 0.75 to 2 in. held nearly flat; very short membranous ligule (bermudagrass has a fringe of hairs); wiry stems rooting at nodes	Green in summer; tan dormant patches in late fall and winter	Penn State; Illinois Extension
Yellow nutsedge (Cyperus esculentus)	Sedge	Perennial	Solid triangular stem; leaves in sets of three, light green and glossy with long tapered tips; straw-colored seedhead; tubers at rhizome tips	Tubers sprout once soil stays above 43°F; new tubers form from late June	UC IPM; Purdue TURF-45; NC State

1. Summer annual3
2. Winter annual3
3. Perennial8

Source: The Green Industry Report compilation of land-grant extension weed guides (UMD, Penn State, NC State, UC IPM, UF/IFAS, UConn, Purdue) Counts are of the rows in the identification chart above. Yellow woodsorrel (annual or perennial) is counted as perennial.

Show the numbers

	Broadleaf	Grassy weed	Sedge
Summer annual	3	1	0
Winter annual	3	1	0
Perennial	8	3	1

Perennials dominate the chart, and they are the weeds that survive mowing and come back from roots. Purdue and Illinois note that broadleaf weed seed persists in soil for 30 or more years (Purdue AY-9), so a weed-free lawn is not a realistic target. For crabgrass dates and products, see our crabgrass guide; for the full grass-and-tree library, the Turf and Trees section.

How do you tell broadleaf weeds, grassy weeds and sedges apart?

Check the leaf veins, then the stem. Broadleaf weeds have net-like veins; grasses have parallel veins and hollow, round stems with joints; sedges have solid, triangular stems you can feel by rolling them between your fingers (UF/IFAS ENH884). UC IPM notes fluazifop kills only grasses (UC IPM), and Purdue says the products used on dandelions and crabgrass miss nutsedge (Purdue TURF-45), so this first call matters.

1. Pull one plant with roots. Note a taproot (dandelion), creeping stems rooting at nodes (ground ivy, white clover) or small tubers (nutsedge) (UGA B-978).
2. Look at the leaf veins. Net veins mean a broadleaf; parallel veins mean a grass or sedge (UF/IFAS). Plantains are the exception: broadleaf weeds whose veins run parallel to the leaf edge (UC IPM).
3. Roll the stem. Triangular and solid is a sedge; round and hollow with joints is a grass; square is a mint-family broadleaf such as ground ivy, henbit or purple deadnettle (UMD; Penn State).
4. Break a stem. Milky sap points to dandelion or spurge (UMD; Penn State).
5. Note the month. A weed flowering in March or April that sprouted last fall is a winter annual; a grass that appears in June or July and dies at frost is a summer annual (UGA; UW-Madison).

Feature	Broadleaf weeds	Grassy weeds	Sedges	Source
Leaf veins and arrangement	Net-like	Parallel; leaves in sets of 2	Parallel; leaves in sets of 3	UF/IFAS ENH884; UC IPM key
Stem	Varies; square in the mint family	Round, hollow, with nodes	Triangular, solid	UF/IFAS ENH884
Seed leaves at sprouting	Two (dicot)	One (monocot)	One (monocot)	UF/IFAS ENH884
Examples in lawns	Dandelion, clover, plantain, ground ivy, spurge	Crabgrass, goosegrass, annual bluegrass, dallisgrass	Yellow and purple nutsedge, kyllinga	UF/IFAS; UMD
Herbicide class that targets it	Selective broadleaf mixes (2,4-D, MCPP, dicamba)	Preemergents for annuals; spot glyphosate for perennials	Halosulfuron, sulfentrazone or sulfosulfuron, two applications	Purdue AY-9; UC IPM

1. 1Is the stem triangular and solid when you roll it between your fingers?

   YesSedge, most likely yellow or purple nutsedge. Dry out the site and use a sedge herbicide (UF/IFAS, UC IPM).

   NoGo to the next question

2. 2Are the leaf veins parallel and the stem round and hollow with joints?

   YesGrassy weed. Check the leaf tip, ligule and seedhead in the look-alike table.

   NoGo to the next question

3. 3Is the stem square?

   YesMint-family broadleaf: ground ivy if it roots at the nodes, henbit or purple deadnettle if it does not (NC State, UMD).

   NoGo to the next question

4. 4Does a broken stem leak milky sap?

   YesDandelion if it is a rosette with yellow heads; spurge if it is a flat mat with purple leaf blotches.

   NoGo to the next question

5. 5Does each leaf have three leaflets?

   YesWhite clover (oval leaflets, watermark), black medic (yellow flowers, tiny tip on the middle leaflet) or oxalis (heart-shaped leaflets).

   NoAnother broadleaf weed: match the leaf shape, flower and season in the 20-weed chart.

Source: UF/IFAS ENH884; NC State TurfFiles; University of Maryland Extension

Which broadleaf weeds are most common in lawns?

Broadleaf weeds are the largest group in most lawns, and their life cycle sets the control date. Winter annuals sprout in late summer and fall and die in late spring; summer annuals sprout in spring; perennials such as dandelion live for years (UGA B-978). The 14 broadleaf weeds in the chart split into these three groups.

Whether a dandelion counts as a weed at all depends on where it grows: it is on none of the 51 state noxious-weed seed lists, a gap our page on whether dandelions are weeds or flowers lays out list by list.

Winter annuals: chickweed, henbit and purple deadnettle

Winter annuals germinate from late summer through fall, overwinter and keep growing in early spring (University of Maryland Extension). Chickweed sprouts best at about 55 to 65°F (UMD), so a late-summer preemergent stops it before it shows.

Henbit and purple deadnettle are both square-stemmed mints. Henbit’s upper leaves clasp the stem with no stalk, while purple deadnettle’s upper leaves have short stalks and a red or purple tinge (NC State TurfFiles). Deadnettle often dies back in mid to late spring before broadleaf sprays go down (Penn State), so a spring spray usually arrives after the plants are already finishing.

Weed	Stem	Leaves	Growth habit	Flower	Source
Ground ivy (perennial)	Square	Opposite, kidney-shaped, scalloped, 0.5 to 1.5 in.	Creeping mats that root at the nodes	Blue-purple, April and May	UMD; NC State
Henbit (winter annual)	Square	Rounded, scalloped; upper leaves clasp the stem with no stalk	Does not creep or root at the nodes	Pink-purple tubes 1/2 to 3/4 in.	UMD; UW-Madison
Purple deadnettle (winter annual)	Square	Fuzzy, triangular, red or purple at the top; upper leaves short-stalked	Upright stems above the turf canopy	Pinkish-purple tubes about 1/2 in.	Penn State; NC State
Common chickweed (winter annual)	Round, with a line of hairs	Opposite, smooth-edged, pointed, 1/2 to 1 in.	Dense mats; stems up to 20 in. root at the nodes	White; 5 split petals look like 10	Penn State; Cornell

Summer annuals: spurge, black medic and lespedeza

Summer annual broadleaf weeds sprout after the soil warms and die at frost. Spotted spurge emerges in early to mid-summer and can flower within 3 to 4 weeks (NC State), which is why Purdue calls summer annual broadleaf weeds very difficult to control with a single spray (Purdue AY-9).

Black medic and common lespedeza both carry three small leaflets and both point to dry, under-fed turf. Tell them apart by the middle leaflet: on black medic it sits on its own short stalk, while all three lespedeza leaflets attach the same way (UMD). Lespedeza hardens off and becomes hard to control as summer goes on (Mississippi State Extension), so treat it in late spring.

Perennials: dandelion, clover, plantain, ground ivy, violet and oxalis

Perennials come back from storage organs, so pulling the top rarely works. A dandelion taproot sits mostly in the top 6 to 18 inches of soil, and root sections as short as 1 inch can regrow (UC IPM). Purdue and Illinois rank ground ivy and wild violets among the hardest because they spread by creeping stems or rootstocks and may need several applications (Purdue AY-9).

Two perennials matter mostly in the South. LSU calls Virginia buttonweed one of the leading weeds of Southern lawns and reports it often takes 4 herbicide applications to keep in check (LSU AgCenter). Dollarweed’s round leaves with a center-attached stalk mark a lawn that stays wet; UF/IFAS calls it a reliable indicator of wet environments (UF/IFAS EP634). Clover is the one perennial some owners keep on purpose; our clover lawn guide weighs that trade.

Which weeds look like grass, and how do you spot them?

Five grassy weeds and one sedge account for most grass look-alikes in lawns: annual bluegrass, goosegrass, dallisgrass, quackgrass, nimblewill and yellow nutsedge, plus crabgrass. Separate them by leaf tip, ligule and auricles, stem shape and seedhead. UC IPM’s quickest test: nutsedge stems are solid and triangular, grass stems hollow and round (UC IPM).

Weed	Leaf tip and blade	Ligule, auricles, stem	Seedhead or other giveaway	Source
Annual bluegrass	Boat-shaped tip; light green, crinkled blades 1 to 3 in.	Membranous ligule 1 to 3 mm; no auricles	Whitish seedheads in spring even at low mowing heights	UC IPM; NC State
Goosegrass	Folded in the bud; flat, mat-forming rosette	Jagged ligule 1 to 1.5 mm, split in the center; no auricles	White to silver flattened center; 2 to 7 zipper-like spikes	Penn State; Cornell
Dallisgrass	Coarse, gray-green, 1/4 to 1/2 in. wide	Ligule about 1/4 in.; no auricles	Clumps with ring-jointed rhizomes; 2 to 10 drooping branches	UC IPM
Quackgrass	Blades 1/8 to 1/2 in. wide	Ligule 1/32 in.; long claw-like auricles clasp the stem	Long white rhizomes with sharp tips	Illinois Extension
Nimblewill	Blue-green, 0.75 to 2 in., held nearly flat	Very short membranous ligule (bermudagrass: fringe of hairs)	Tan dormant patches late fall to spring	Penn State
Crabgrass	Wider and paler than bluegrass or fescue	Short membranous ligule; no auricles	3 to 11 finger-like spikes leaving the stem 1/8 to 1/4 in. apart; roots at nodes	our crabgrass guide; NC State
Yellow nutsedge (sedge)	Glossy, yellow-green, long tapered tip; leaves in threes	No ligule; solid triangular stem	Straw-colored seedhead; tubers at rhizome tips	UC IPM; NC State

Season is a free clue. In Wisconsin, a coarse grass that is green and mature in April or May cannot be crabgrass, which does not show until warm weather well into June or July (UW-Madison Extension). Annual bluegrass is the reverse: it sprouts as soil falls below 70°F in late summer and flowers in spring (UC IPM).

Perennial grass weeds are the hardest group because the lawn is also a grass. Illinois Extension says no selective herbicide controls quackgrass in lawns, so the option is spot glyphosate and reseeding (Illinois Extension); UC IPM says dallisgrass needs at least 3 applications and that renovating a heavily infested home lawn is often cheaper (UC IPM).

The same biology is why 2,4-D, the active in most lawn weed killers, leaves quackgrass, dallisgrass and crabgrass alone, as our label-by-label answer to does 2,4-D kill grass explains.

Nutsedge needs its own herbicides: Purdue recommends halosulfuron or sulfentrazone (Purdue TURF-45). Purple nutsedge, the warm-season relative, forms tubers in chains, has a reddish-purple seedhead and is much harder to control (NC State TurfFiles). Purdue expects 2 to 3 years of control to cut viable yellow nutsedge tubers by 90 percent.

What do lawn weeds say about your soil and lawn care?

Some weeds cluster where the grass is losing for a reason you can fix. UC IPM’s lawn guide ties annual bluegrass, goosegrass and dallisgrass to overwatering and compacted soil, and black medic and white clover to low nitrogen (UC IPM Pest Notes 74113). UConn adds shade: turf needs at least 4 to 6 hours of sun a day (UConn Extension).

Condition	Weeds extension guides tie to it	What to check or change	Source
Compacted soil	Annual bluegrass, goosegrass, prostrate knotweed, broadleaf plantain, spotted spurge, dandelion, white clover	Core-aerate; overseed with compaction-tolerant perennial ryegrass	UConn; UC IPM
Wet soil, overwatering or poor drainage	Yellow nutsedge, common chickweed, annual bluegrass, dollarweed, ground ivy	Cut irrigation; fix drainage before spraying	UConn; UMD; UF/IFAS
Low nitrogen	White clover, black medic, spurges (UC IPM); plantain, red sorrel (UConn)	Soil test, then feed at the rate for your grass	UC IPM; UConn
Dry, infertile soil	Common lespedeza, buckhorn plantain, black medic	Water deeply and less often; add organic matter	UMD; UC IPM; UConn
Shade, under 4 to 6 hours of sun	Ground ivy, violets, nimblewill, moss, annual bluegrass, chickweed	Prune trees; overseed fine or tall fescue; Kentucky bluegrass needs over 6 hours	UConn
Mowing too short	Crabgrass, spurges, henbit	Raise the deck; take no more than one-third of the blade	UC IPM; UMD

UF/IFAS puts the logic in one line: “weeds don’t create a void; they fill a void” (UF/IFAS ENH884). If the condition stays, the weed returns after any herbicide, which is why UConn tells readers to correct the soil or site before spraying (UConn Extension). Our guide to when to aerate your lawn covers the compaction fix by grass type.

Wet-soil weeds are the clearest signal. UF/IFAS says nutsedges thrive where soil stays wet from poor drainage or excess irrigation and that the first step is correcting the wet site (UF/IFAS). Our lawn watering guide shows how to measure what a sprinkler puts down.

Are weeds reliable signs of soil pH and nutrients?

Only loosely. Extension lists tie weeds to compaction, wetness, shade and low nitrogen, but popular pH and calcium claims mostly fail against weed-biology research. Cornell reports dandelion grows better at pH 7.1 than at 6.2 (Cornell), and two extension services file broadleaf plantain under opposite pH conditions. Test the soil instead of reading the weeds.

Claim in popular guides	What the primary source says	Source
Dandelions mean acidic soil with high potassium and low calcium (LawnStarter, Oct. 2026)	Half right. High potassium does favor dandelion over grasses, but growth increases up to pH 8, soil at pH 7.1 gave 45 percent more fresh weight and 67 percent more plants than pH 6.2, and excessive liming promotes it	Cornell Weed Science, dandelion profile
Oxalis signals moist soil high in magnesium and low in calcium (LawnStarter)	Cornell calls yellow woodsorrel an indicator of moist, fertile soil that also tolerates drought; Penn State finds it in sun and shade, moist and dry soil. Neither names magnesium or calcium	Cornell; Penn State
Crabgrass means high fertility from over-fertilizing (LawnStarter)	UConn lists crabgrass among weeds of low-fertility and drought-prone soils; UC IPM ties it to frequent light watering and mowing too short	UConn; UC IPM
Broadleaf plantain marks acidic soil (UConn table)	UC IPM calls broadleaf plantain an indicator of alkaline (high pH), low-fertility, compacted soil; Cornell links both plantains to fields at pH 6.5 to 7.8	UC IPM; Cornell
Clover means compacted, acidic soil (LawnStarter)	Penn State and UC IPM tie white clover to low nitrogen; UConn files it under low fertility, drought and compaction, not acidity	Penn State; UConn

The pH figures below show why a weed is a poor pH meter. UConn’s target for turf is pH 6.0 to 7.2 (UConn), and every weed in the table tolerates or prefers part of that range. The chart plots the same numbers; the column on the right says what each figure measures, because the studies did not measure the same thing.

Plant	Soil pH figure	What the figure means	Source
Turfgrass target	6.0 to 7.2	Range to maintain for nutrient availability	UConn
Dandelion	4.0 to 8.0	Tolerates 4.0; growth rises up to 8; poor below 5.2	Cornell
Common chickweed	5.2 to 8.2	Grows well; severely depressed below 5.2	Cornell
Henbit	5.0 to 7.0	Density insensitive to pH on sandy soil	Cornell
Annual bluegrass	5.5 to 6.5	Best growth; rarely found below 5.3	Cornell
Broadleaf and buckhorn plantain	6.5 to 7.8	pH of fields where they occurred	Cornell
Goosegrass	5.0 to 10.0	Seeds germinate well across this range	Cornell

1. Turf target6
2. Dandelion4
3. Common chickweed5.20
4. Henbit5
5. Annual bluegrass5.50
6. Plantains6.50
7. Goosegrass5

Source: Cornell Weed Science weed profiles; UConn Extension (turf target) Figures measure different things: tolerance (dandelion), good growth (chickweed), insensitivity (henbit), best growth (annual bluegrass), field occurrence (plantains), germination (goosegrass). Values are in the table above.

Show the numbers

	Low end of pH figure	High end of pH figure
Turf target	6	7.20
Dandelion	4	8
Common chickweed	5.20	8.20
Henbit	5	7
Annual bluegrass	5.50	6.50
Plantains	6.50	7.80
Goosegrass	5	10

The practical rule: a weed tells you the turf is weak, not which nutrient is off. Cornell even finds that excessive liming promotes dandelion (Cornell), so liming to fight dandelions can backfire. UConn recommends a soil test every 1 to 3 years to track pH and nutrients (UConn); our soil test guide covers how to take one.

When should you control each type of lawn weed?

Time control to the life cycle. Preemergents go down 2 to 3 weeks before annual weeds germinate: early spring for crabgrass and goosegrass, early fall for annual bluegrass, chickweed and henbit (UC IPM; UGA). Perennial broadleaf weeds die best to a fall spray, mid-September to early November in Indiana (Purdue AY-9).

Weed group	Examples	Control window	Trigger or limit	Source
Summer annual grasses	Crabgrass, goosegrass	Preemergent in early spring; goosegrass 3 to 4 weeks later	Crabgrass germinates when soil holds 55 to 60°F for about a week: mid-March to mid-April in central Maryland	UMD; UF/IFAS
Summer annual broadleaf weeds	Spurge, knotweed, lespedeza, black medic	Spray small plants in late spring to early summer; isoxaben preemergent in April	One spray may miss later flushes	Purdue AY-9; NC State
Winter annuals	Annual bluegrass, chickweed, henbit, deadnettle	Preemergent late summer to early fall; spray small plants October to November	Florida: when nights drop to 55 to 60°F for several days	UGA B-978; Purdue; UF/IFAS
Perennial broadleaf weeds	Dandelion, clover, plantain, ground ivy, violet	Mid-September to early November; second choice late spring after flowering	Air 50 to 85°F, moist soil, no mowing 3 days before or after	Purdue AY-9
Perennial grasses	Dallisgrass, quackgrass, nimblewill, bermudagrass in fescue	Spot-spray glyphosate or fluazifop while actively growing, best early fall	Kills the lawn grass it touches; reseed after	UC IPM; UW-Madison
Sedges	Yellow and purple nutsedge	Early summer, before the fifth leaf and before new tubers form in late June; 2 applications	No preemergent kills nutsedge tubers in cool-season turf	UC IPM; UC IPM pn7432; NC State

Late fall still counts. Purdue’s turf program reports broadleaf herbicides applied in Indiana until about mid-November still give effective control, and that November applications on ground ivy matched September and October when rated the next June (Purdue Turfgrass Science). Winter annuals are small then, so the same spray takes henbit, chickweed and deadnettle.

Two limits apply to new lawns. UGA recommends preemergents only on turf established for at least one year (UGA B-978), and Purdue waits until new seedlings have been mowed three times, or 4 to 6 weeks on new sod, before a broadleaf herbicide (Purdue AY-9). Our lawn care schedule places these windows in a month-by-month calendar.

Step	Input	Arithmetic	Result
1. Summer-annual preemergent, central Florida	UF/IFAS rule of thumb: Feb. 15	Start date as published	Feb. 15
2. Goosegrass is the main weed	Wait 3 to 4 weeks longer	Feb. 15 + 21 days; Feb. 15 + 28 days	Mar. 8 to Mar. 15
3. Season-long cover	Second application 6 to 9 weeks after the first	Feb. 15 + 42 days; Feb. 15 + 63 days	Mar. 29 to Apr. 19
4. Winter-annual preemergent, same lawn	Nights at 55 to 60°F; late Oct. to early Nov. in central Florida	Date as published	Late Oct. to early Nov.
5. Central Maryland crabgrass	Germination mid-Mar. to mid-Apr. (UMD); apply 2 to 3 weeks earlier (UC IPM)	Mar. 15 minus 21 days; Apr. 15 minus 14 days	About Feb. 22 to Apr. 1

Row 5 is a wide window because it combines a germination range with a lead time. Narrow it with a soil thermometer: the 55°F trigger and city-by-city dates are in our crabgrass timing tables.

Which lawn weeds are most common in your region?

The weed list shifts with grass type and climate. Cool-season lawns in New England and the Midwest fight dandelion, ground ivy, violets and quackgrass; the transition zone adds goosegrass, lespedeza and nutsedge; Florida and the Gulf add dollarweed and Virginia buttonweed (UConn; UMD; UGA; UF/IFAS). The table names each region’s weeds from its own extension guide.

Region	Weeds the extension guide names	Regional detail	Source
New England	Crabgrass, annual bluegrass, plantains, white clover, violets, nimblewill; ground ivy and Japanese stiltgrass, both listed as Connecticut invasives	Turf needs 4 to 6 hours of sun; Kentucky bluegrass over 6	UConn Extension, 2018
Mid-Atlantic	Chickweed, henbit, deadnettle, annual bluegrass, black medic, lespedeza, spurge, crabgrass, goosegrass, dandelion, ground ivy, plantain, white clover, wild garlic, quackgrass, dallisgrass, nimblewill, yellow nutsedge	Crabgrass germinates mid-March to mid-April in central Maryland	University of Maryland Extension, 2023
Midwest	Dandelion (called the most common lawn weed), ground ivy, wild violet, spurge, knotweed; perennial grass weeds quackgrass, nimblewill, creeping bentgrass, pasture tall fescue	Broadleaf sprays still work in Indiana to about mid-November	Purdue and Illinois AY-9; UW-Madison; Purdue
Southeast and transition zone	Crabgrass, goosegrass, lespedeza, prostrate knotweed, annual bluegrass, chickweed, henbit, nutsedge, dallisgrass, Virginia buttonweed	Virginia buttonweed ranges from New Jersey west to Missouri and south to the Gulf Coast	UGA B-978; UGA B1397
Florida	Dollarweed, goosegrass, annual bluegrass, sedges, Florida pusley, Virginia buttonweed, chamberbitter, lawn burweed	Preemergent by Feb. 1 in south, Feb. 15 in central and Mar. 1 in north Florida	UF/IFAS ENH884, rev. 2024
California	Annual bluegrass, crabgrass, goosegrass, bermudagrass, dallisgrass, burclover, black medic, knotweed, spurges, white clover, creeping woodsorrel, dandelion, English daisy, plantains, kyllinga, nutsedge	English daisy is mostly a moist, cool coastal-climate weed	UC IPM Pest Notes 74113

Lawn burweed, which Mississippi State says is also called sticker weed or spurweed, is a winter annual that germinates from October to December and forms spiny burs in spring; once the burs form, control is futile (Mississippi State Extension Publication 4180). UF/IFAS lists it among the annual broadleaf weeds a fall preemergent controls, applied when Florida nights fall to 55 to 60°F for several days (UF/IFAS ENH884).

What should you do about the weeds in your lawn?

Match the response to the weed group and the density. A few perennial broadleaf weeds get a fall spot spray; a weed that tracks a site problem gets the site fixed first; annual grasses get a preemergent next season; a lawn that is mostly weeds gets renovated (UC IPM; Purdue AY-9). The table and flowchart below hold the same logic.

If your situation is	Do this	Why (source)
Less than half the lawn is the grass you want	Renovate: kill, remove, fix the cause, replant	Kentucky suggests re-establishing below 50 percent desired turf (UK AGR-51); Minnesota when weeds cover about 30 to 50 percent and turf cannot fill in (UMN)
Scattered dandelions, clover or plantain	Spot-spray mid-September to early November; dig a few by hand	Fall sprays gave over 90 percent dandelion control vs 50 percent or less in spring (K-State; Purdue AY-9)
Ground ivy or wild violet patches	Triclopyr or fluroxypyr after the first fall frost; plan repeat sprays	Best actives and timing (Penn State; Penn State)
Crabgrass or goosegrass last summer	Preemergent 2 to 3 weeks before germination; redo 6 to 8 weeks later for goosegrass	(UC IPM; Penn State)
Annual bluegrass, chickweed or henbit last spring	Preemergent in late summer as soil falls below 70°F	(UC IPM; UMD)
Nutsedge or dollarweed in a wet spot	Cut irrigation and fix drainage, then a sedge herbicide in early summer	Weeds fill a void (UF/IFAS); timing (UC IPM)
Quackgrass, dallisgrass or nimblewill patches	Spot glyphosate and reseed; mesotrione series for nimblewill	(Illinois; UC IPM; Illinois)
Weeds concentrated in shade	Prune or overseed fine or tall fescue; herbicide alone will not hold	Turf needs 4 to 6 hours of sun (UConn)
Lawn seeded or sodded this year	No preemergent until established 1 year; broadleaf spray after 3 mowings or 4 to 6 weeks on sod	(UGA B-978; Purdue AY-9)

1. 1Is less than half the lawn the grass you want?

   YesRenovate: fix the cause, kill and remove the old turf, replant (UK AGR-51, UC IPM).

   NoGo to the next question

2. 2Do the weeds sit in a wet, compacted or shaded spot?

   YesFix the site first: drainage and watering, core aeration, or more light and a shade grass (UConn, UF/IFAS).

   NoGo to the next question

3. 3Are they perennial broadleaf weeds such as dandelion, clover or ground ivy?

   YesSpot-spray mid-September to early November at 50 to 85°F (Purdue AY-9).

   NoGo to the next question

4. 4Are they annual grasses or winter annuals that came back this year?

   YesPlan a preemergent 2 to 3 weeks before next germination (UC IPM).

   NoGo to the next question

5. 5Are they nutsedge or perennial grasses?

   YesSedge herbicide in early summer, or spot glyphosate and reseed (UC IPM, Illinois).

   NoHand-pull young weeds with the root and keep mowing height and feeding right for your grass (UC IPM).

Source: UC IPM Pest Notes 74113; Purdue AY-9; UConn; UF/IFAS ENH884; UK AGR-51

Product choice by active ingredient, rates, temperature limits and the grasses each herbicide injures are covered in our lawn weed killer guide; household vinegar’s limits are in our vinegar weed killer review. Applying herbicides on someone else’s lawn for pay requires a state license, explained in our pesticide applicator license guide.

Question	Number to use	Source
Is it broadleaf, grass or sedge?	Net veins = broadleaf; hollow round stem = grass; solid triangular stem = sedge	UF/IFAS
When to spray perennial broadleaf weeds	Mid-September to early November, at 50 to 85°F	Purdue AY-9
When to apply a preemergent	2 to 3 weeks before germination; crabgrass at 55 to 60°F soil	UC IPM; UMD
Target soil pH for turf	6.0 to 7.2	UConn
Minimum sun for turf	4 to 6 hours a day	UConn

This page is general information, not pesticide advice. The label is the law: read and follow the label on any herbicide you buy, and check your state’s rules before applying it.