Crabgrass
Grassy weed
Crabgrass is a warm-season annual grass that shows up in lawns, gardens, and field edges across most of the United States. Gardeners and growers notice it because it germinates fast in bare or thin spots and can take over an area by late summer. Two species are common: large (hairy) crabgrass and smooth crabgrass.
How to identify it
Young plants have light green, coarse blades that are wider than most lawn grasses, often with fine hairs near the base on hairy crabgrass. The plant grows low and spreads outward in a star or crab-leg pattern, with stems that bend at the joints and root where they touch soil. In mid to late summer it sends up finger-like seed heads, usually with several spikelets branching from one point like a fork. A single plant can reach a foot or more across when it has room.
Where it grows
Crabgrass grows in lawns, vegetable and flower beds, cropland, sidewalk cracks, and any disturbed or compacted soil. It favors full sun and warm soil, so it appears along driveways, curbs, and thin lawn edges first. Seeds sprout once soil warms in spring and the plant sets thousands of seeds before dying at the first hard frost, and those seeds carry over in the soil for years.
Why it is a problem
Crabgrass competes with lawn grass, vegetables, and young crops for water, light, and nutrients, and its fast spread can crowd out desirable plants by season's end. One plant produces thousands of seeds, so a small patch this year can become a large infestation next year. When it dies back in fall it leaves bare patches that invite more weeds and erosion.
How to manage it
The best defense is a thick, healthy lawn or a well-mulched bed, since crabgrass seeds need sunlight on bare soil to sprout; mow at the taller end of your grass's range and avoid scalping to keep the ground shaded. Pull young plants by hand before they set seed, getting the rooting stem joints, and cover open garden soil with two to three inches of mulch. Water deeply but less often to favor deep-rooted turf over shallow crabgrass, and reseed or overseed thin spots in fall so weeds have no room to establish. Correcting compaction and improving drainage also makes conditions less friendly to it.
Commonly confused with
Crabgrass is often confused with goosegrass, which forms a flatter rosette with a whitish center, and with young bermudagrass or tall fescue clumps. Checking for the crab-leg spreading habit and the forked, finger-like seed heads helps tell it apart.
General guidance for US lawns and gardens, focused on prevention and non-chemical control. For a confirmed identification and options specific to your area, contact your local Cooperative Extension office. Page updated Aug 4, 2026.