Crabgrass or Bermuda Grass? A Measured ID Key From 8 Universities

We put the identification keys from 8 university extension services side by side and kept only the features that do not overlap. Three of them settle almost every case: the ligule (membrane vs hairs), blade width (NC State measures bermudagrass at 1.5 to 3 mm and crabgrass at 5 mm or more) and whether the plant survived last winter. The feature most people reach for, counting the fingers on the seedhead, is the weakest: the published spike counts overlap at 3 to 5 for both grasses. What separates the seedheads is where the fingers attach, and UC IPM gives that gap in fractions of an inch.

Six checks, fastest first

Work down the list and stop at the first check that gives a clear answer. Check 5 or 6 full-size, healthy leaves from the middle of the patch: seedlings, scalped shoots and drought-curled leaves read narrower and hide the ligule. A ruler with 1 mm marks and a phone camera on macro are the only tools needed.

1. Did it live through winter? A patch that sat as a tan mat from the first frost to spring and greened up from the same runners is bermudagrass. Crabgrass turns reddish-brown and dies after fall frosts (Penn State), so nothing green or tan stays rooted in the spot over winter, except in frost-free coastal California where UC IPM says plants can overwinter.
2. Pull one stem and dig 3 inches down. Bermudagrass has above-ground stolons with a papery sheath at each node and below-ground rhizomes, usually 1 to 6 inches deep in undisturbed soil (UC IPM). Crabgrass has no rhizomes; its stems fan out from one crown and only root where a lower node lies on the soil.
3. Bend the leaf back at the collar. A fringe of white hairs 1 to 3 mm long is bermudagrass. A thin, see-through membrane, 1 to 3 mm tall and often toothed or reddish on large crabgrass, is crabgrass (NC State, large crabgrass).
4. Measure the blade at its widest point. 3 mm (1/8 inch) or narrower points to bermudagrass; 5 mm (3/16 inch) or wider points to crabgrass. No extension key we read puts either species between 3.2 mm (UGA’s 1/8 inch for bermudagrass) and 5 mm.
5. Roll the newest leaf open. Bermudagrass leaves are folded in the bud, creased flat like a closed book; crabgrass leaves are rolled, round in cross-section (UF/IFAS EP646; NC State, smooth crabgrass).
6. If a seedhead is present, look at where the fingers leave the stem. All from one point is bermudagrass. Spaced about 1/8 to 1/4 inch apart up the tip of the stalk is crabgrass, and fingers longer than 2 1/2 inches can only be large crabgrass (UC IPM).

1. 1Did the patch stay rooted as a tan mat through winter and green up from the same runners?

   YesBermudagrass. Crabgrass dies after fall frost (Penn State).

   NoGo to the next question

2. 2Digging 3 inches down, do you find white, jointed rhizomes?

   YesBermudagrass. Crabgrass has no rhizomes (UC IPM; NC State).

   NoGo to the next question

3. 3Bent back, is the ligule a fringe of hairs rather than a papery membrane?

   YesBermudagrass (fringe of hairs 1 to 3 mm, NC State).

   NoGo to the next question

4. 4Is a full-size blade 5 mm (3/16 inch) wide or wider?

   YesCrabgrass. Bermudagrass blades are 1.5 to 3 mm (NC State).

   NoGo to the next question

5. 5Do the seedhead fingers leave the stem 1/8 to 1/4 inch apart?

   YesCrabgrass. Bermudagrass fingers all start at one point (UC IPM).

   NoStill unsure: mark the patch and check it in January, or compare against goosegrass and dallisgrass in our common lawn weeds chart.

Source: UC IPM; NC State TurfFiles; Penn State Extension

The ID key, with each university’s measurement

Every cell below is a value printed in one of 12 extension documents, not an estimate. Where two sources give different numbers, both are shown so you can see how wide the published range really is. Smooth crabgrass (Digitaria ischaemum) is the common lawn species; large or hairy crabgrass (D. sanguinalis) is hairier and coarser.

Swipe the table sideways to see every column.

Feature	Crabgrass	Bermudagrass	Source
Life cycle	Summer annual; dies after fall frost	Warm-season perennial; dormant and tan in winter	Penn State; UC IPM
Ligule	Membrane: 1 to 2 mm, toothed, often reddish (large); 1.5 to 3 mm, blunt, slightly wavy (smooth); Penn State: 1 to 1.5 mm	Fringe of hairs, 1 to 3 mm	NC State; NC State; NC State; Penn State
Vernation (newest leaf)	Rolled in the bud	Folded in the bud	NC State; Virginia Tech; UF/IFAS; UGA
Blade width	5 to 10 mm (smooth); 5 to 15 mm (large); UC IPM: 1/4 to 1/3 inch for smooth	1.5 to 3 mm; UGA and K-State: 1/8 inch	NC State; NC State; UC IPM; K-State MF2031
Blade length	Up to 5 in (smooth); about 3 in in turf (large)	Short	UC IPM; UGA
Leaf hairs	Large: short hairs on both surfaces, long hairs on sheath. Smooth: a few hairs near the blade base	Smooth or sparsely hairy; edges rough	NC State; NC State; UGA
Collar	Large: flattened, hairy sheath, often purple veins. Smooth: divided, few hairs at edge	Narrow; UGA and K-State: covered with long hairs	NC State; NC State; K-State
Auricles	Absent	Absent	NC State; UF/IFAS
Growth habit	Tillers radiate from one crown, flat rosette; more than a dozen tillers by late summer	Mat with no single center; uneven spacing between leaves on runners	Penn State; UF/IFAS
Runners and rhizomes	No rhizomes; prostrate stems may root at lower nodes	Stolons and rhizomes, both stout; rhizomes 1 to 6 in deep	NC State; NC State; UC IPM
Seedhead attachment	Fingers leave the stem about 1/8 to 1/4 in apart	All fingers from one point	UC IPM; UC IPM
Spikes per seedhead	5 to 7 (smooth), 3 to 11 (large) per UC IPM; 2 to 9 per NC State	3 to 7 per UC IPM; 3 to 5 per NC State, UF and UGA	UC IPM; NC State
Spike length	1/2 to 2 1/2 in (smooth); 2 to 5 in (large)	1 to 2 in	UC IPM; UC IPM
Seedling	Fat seed leaf; large crabgrass hairy on every leaf and stem	Fine, folded leaves from seed or runners	Virginia Tech; UF/IFAS
Germination or green-up	Seed sprouts at 53 to 58°F soil at 4 in, March to early May in North Carolina	Greens up from runners; NC State first feeding comes several weeks after full green-up, early April to May	NC State; NC State calendar

Ligule length does not separate them: both are 1 to 3 mm. What separates them is what the ligule is made of. A membrane catches light like a thin film of plastic; a fringe of hairs looks like a short white eyelash line when the blade is bent back. The NC State profiles below show both, with the measured lengths highlighted.

Blade width: the ruler test

Blade width is the fastest field check because it needs no magnifier. NC State puts bermudagrass at 0.06 to 0.1 inch (1.5 to 3 mm), and UGA and K-State both say 1/8 inch, about 3.2 mm. The narrowest crabgrass in the same keys is 5 mm: NC State gives 5 to 10 mm for smooth and 5 to 15 mm for large crabgrass, and UC IPM gives 1/4 to 1/3 inch (6.4 to 8.5 mm) for smooth.

1. Bermudagrass, NC State1.50
2. Bermudagrass, UGA and K-State (1/8 in)3.20
3. Smooth crabgrass, NC State5
4. Smooth crabgrass, UC IPM6.40
5. Large crabgrass, NC State5

Source: NC State TurfFiles; UGA; K-State MF2031; UC IPM Inch values converted at 25.4 mm. Penn State's 1/2 to 3/4 in for crabgrass is left out as an outlier; see the disagreement table.

Show the numbers

	Narrowest	Widest
Bermudagrass, NC State	1.50	3
Bermudagrass, UGA and K-State (1/8 in)	3.20	3.20
Smooth crabgrass, NC State	5	10
Smooth crabgrass, UC IPM	6.40	8.50
Large crabgrass, NC State	5	15

Two cautions apply. Common bermudagrass is coarser than hybrids such as Tifway and TifTuf, and NC State notes it has a wider blade and more seedheads, so measure 5 or 6 leaves and use the widest. And Penn State prints crabgrass blades as 1/2 to 3/4 inch wide, 2 to 3 times what NC State and UC IPM give; if your crabgrass measures 6 mm, it still fits the majority of the keys.

Seedheads: measure the gap, do not count the fingers

Both grasses carry finger-like spikes from midsummer, and the counts published for them overlap almost completely. Penn State and Virginia Tech give crabgrass 3 to 5 spikes; NC State, UF/IFAS and UGA give bermudagrass 3 to 5. A 4-finger seedhead fits every key for both species.

1. Smooth crabgrass, UC IPM5
2. Large crabgrass, UC IPM3
3. Large crabgrass, NC State2
4. Smooth crabgrass, NC State2
5. Crabgrass, Penn State3
6. Large crabgrass, Virginia Tech3
7. Bermudagrass, UC IPM3
8. Bermudagrass, NC State3
9. Bermudagrass, UF/IFAS3
10. Bermudagrass, UGA3

Source: UC IPM; NC State TurfFiles; Penn State; Virginia Tech; UF/IFAS EP646; UGA Every key allows 3 to 5 spikes for both grasses. NC State's large crabgrass profile says 2 to 9 spikelets, read here as spikes.

Show the numbers

	Fewest	Most
Smooth crabgrass, UC IPM	5	7
Large crabgrass, UC IPM	3	11
Large crabgrass, NC State	2	9
Smooth crabgrass, NC State	2	6
Crabgrass, Penn State	3	5
Large crabgrass, Virginia Tech	3	5
Bermudagrass, UC IPM	3	7
Bermudagrass, NC State	3	5
Bermudagrass, UF/IFAS	3	5
Bermudagrass, UGA	3	5

The difference is the attachment. UC IPM says crabgrass fingers originate about 1/8 to 1/4 inch apart at the end of the stem, while bermudagrass and goosegrass fingers originate at the same point. Hold the stalk against a ruler: a 3 to 6 mm stretch of stem carrying the fingers is crabgrass. The top Google result for this query, a grass-ID app page, tells readers the seedhead alone cannot separate the two; on attachment, UC IPM says it can.

What each grass looks like by season

The calendar is the check that needs no close-up at all. Crabgrass seed sprouts when the soil 4 inches down reaches 53 to 58°F (NC State), which is March to early May in North Carolina, and plants die with the first frost. Bermudagrass is present all year as runners and only changes color.

Months	Crabgrass	Bermudagrass	Source
December to February	Nothing alive where frost has occurred; seed waits in the soil	Tan, dormant mat; runners still rooted and pliable	Penn State; UC IPM
March to early May	Seedlings appear once soil at 4 in holds 53 to 58°F; pale, single-crown plants in bare or thin spots	Greens up from existing runners and crowns	NC State; NC State calendar
May to June	Tillers spread flat from one crown; peak germination a few weeks after the first	New runners cross bare soil, edges and pavement	Penn State; UC IPM
July to September	Seedheads; one large plant can shed more than 100,000 seeds	Seedheads, more on common than on hybrid types	UC IPM; NC State calendar
October to November	Turns reddish-brown, then dies after frost; Central Valley California typically late October	Goes tan after frost, stays rooted	Penn State; UC IPM

This makes a summer guess testable. If you cannot decide by August 31, flag the patch with a stake and look again in January: a bare spot means crabgrass, a tan mat that peels up in runners means bermudagrass.

Where the published keys disagree

Question	One source says	Another says	What to do with it
Does crabgrass have stolons?	UC IPM: no rhizomes or stolons	NC State: stolons present, rhizomes absent	Treat crabgrass stems that root at the lower nodes as a weak runner; the test that holds is rhizomes, which only bermudagrass has
Bermudagrass collar hairs	UGA and K-State: collar covered with long hairs	NC State: collar not hairy, may be hairy on edges	Do not rely on the collar; check the ligule hairs just above it
Crabgrass blade width	NC State: 5 to 10 mm (smooth); UC IPM: 1/4 to 1/3 in	Penn State: 1/2 to 3/4 in	Use 5 mm as the lower bound; it is the narrowest figure any key prints
Spikes per bermudagrass seedhead	UC IPM: 3 to 7	NC State, UF/IFAS, UGA: 3 to 5	Ignore the count; check that every spike leaves the same point
Can the seedhead separate them?	A top-ranked ID app page: no	UC IPM: yes, by the 1/8 to 1/4 in spacing	Use the spacing, not the count or the shape

The pull test that several top results lead with has a limit too. A young crabgrass plant does lift out as one crown, but NC State notes that its stems may root at the lower nodes, so a large August plant can hold. The deciding sign after a pull is a white, jointed rhizome below the surface: crabgrass never has one.

What the answer changes

The identification decides which tools work, because one is a seed problem and the other is a root-system problem. UC IPM says preemergence herbicides are generally not a practical way to control bermudagrass in turf, since they do not touch established stolons and rhizomes.

Tool	On crabgrass	On bermudagrass	Source
Spring preemergent	Stops seedlings if down before soil reaches 53 to 58°F at 4 in; mid-February to early March in North Carolina	No effect on established runners	NC State calendar; UC IPM
Hand pulling	Works on young plants before seedheads	Fragments of stolons and rhizomes left in moist soil regrow	UC IPM; UC IPM
Waiting for frost	Kills every plant; the seed bank remains	Only turns it tan	Penn State
Where to go next	Our crabgrass preventer dates and actives	Our bermuda grass removal rates by lawn type	GIR guides

If the patch is bermudagrass in a bermudagrass lawn, it is the lawn: its mowing, feeding and cultivar data are in our bermuda grass guide. If it is spreading into tall fescue, our sibling page on fescue vs bermuda grass compares the two lawns, and the common lawn weeds ID chart covers goosegrass, dallisgrass and the other look-alikes.

This page is identification guidance, not a pesticide recommendation. Any herbicide named here or on our linked pages, such as the quinclorac and topramezone products in the FAQ, must be used only as its EPA-registered label directs; the label is the law.