Large Crabgrass
Digitaria sanguinalis · Warm-season, Annual, C4
Grass Family
Poaceae, subfamily Panicoideae, tribe Paniceae
Grass Category
Invasive/Weed Grass
Variety / Cultivar
Not a cultivar; wild type/weed species
Hardiness Zones
Grows as a summer annual in USDA Zones 2-11. It is killed by the first hard frost but leaves behind thousands of seeds that remain viable in the soil for several years.
About This Grass
A low-growing, spreading summer annual that forms dense, pale green to medium green mats. It is recognized by its finger-like (digitate) seed heads and prostrate stems. In late summer/fall, stems often turn purple or reddish-brown near the base.
Blade Characteristics
Blades are medium-coarse (roughly 5-10mm wide), flat, and tapering to a sharp point. They are notable for being covered in stiff, fine hairs on both surfaces and the sheaths. Ligule is membranous and tall with a jagged edge; auricles are absent. Vernation is rolled in the bud.
Root System
Fibrous and shallow, but highly effective at resource competition. Secondary roots form readily at the nodes (adventitious roots), allowing a single plant to cover a large area. It does not form a dense turf sod but rather a tangled mat that is difficult to pull.
Growing Information
Origin Region
Native to Europe and Asia; highly invasive and naturalized throughout North America and worldwide temperate/tropical regions.
Growth Habit
Stoloniferous and prostrate-spreading. It possesses a decumbent growth habit, meaning stems grow horizontally along the ground and can root at the nodes when they touch soil, forming a radiating, clumped mat.
Sunlight & Water Needs
Requires Full Sun for peak germination and growth. High drought tolerance once established, though it thrives in moist, disturbed soils. Prefers high nitrogen environments and slightly acidic to neutral pH.
Mowing & Maintenance
Maintenance involves eradication rather than cultivation. It can survive mowing heights as low as 0.5 inches by producing seed heads horizontally. Controlling it requires pre-emergent herbicides in early spring when soil temperatures reach 55F, or post-emergent selective herbicides for ornamental beds.
Special Characteristics
Extremely high traffic tolerance due to its prostrate nature. Highly invasive in lawns and gardens. Ability to produce up to 150,000 seeds per plant in a single season. Allelopathic tendencies may inhibit the growth of surrounding desired turf grasses.
Ecological Information
Introduced/Invasive in most regions. While the seeds provide food for some ground-feeding birds and small rodents, it is generally considered a nuisance that disrupts managed turf ecosystems and reduces biodiversity in native grass stands.