Crabgrass is a green weed that resembles lawn grass and appears in clumps. In cool climates, crabgrass has smooth stems and rarely exceeds 6 inches in height. In warmer locales, crabgrass has hairy stalks and grows up to 48 inches tall.
Crabgrass has wider blades than most lawn grass species, and each blade has a central crease. Each stem produces several blades. Crabgrass also grows more rapidly than lawn grass, and propagates quickly in all directions.
Crabgrass is an invasive plant that suffocates lawn grass. Weed killers such as Tenacity Turf Herbicide kill crabgrass quickly. However, many of these products also damage lawns and ornamental plants.