Smooth Crabgrass
Digitaria ischaemum · Warm-season, Annual, C4
AI-generated identification · may be incorrect
Grass Category
Invasive/Weed Grass
Hardiness Zones
USDA Hardiness Zones 3-10, dies with the first hard frost of autumn.
Grass Family
Poaceae, subfamily Panicoideae, tribe Paniceae
Variety / Cultivar
Wild type (no specific named cultivars for turf weed)
About This Grass
Forms dense, light-green to bluish-green patches with a sprawling, crab-like growth pattern hugging the ground. Reaches 6 to 18 inches tall if left unmowed. Features distinctive finger-like (digitate) raceme seed heads.
Blade Characteristics
Blades are medium-coarse in width (3-8 mm), flat, pointed tips, light green to blue-green color. Rolled in the bud (vernation). Membranous ligule with no auricles.
Root System
Fibrous and shallow root system, often developing roots at the lower stem nodes where they touch the soil. Rapid establishment from seed.
Growing Information
Origin Region
Europe and Asia, now widely naturalized throughout North America and temperate regions globally.
Growth Habit
Stoloniferous and spreading prostrate mat-forming habit, rooting at the lower nodes.
Sunlight & Water Needs
Requires full sun, cannot tolerate dense shade. Moderate to high water needs for active growth, though highly resilient in dry spells via dormancy.
Mowing & Maintenance
High maintenance weed; difficult to control by mowing alone due to prostrate growth habit below standard mowing heights (0.5 to 1.5 inches).
Special Characteristics
Extremely high seed production, highly invasive in thin lawns, excellent adaptation to compacted soils and high heat.
Ecological Information
Introduced weed species, provides minimal wildlife value compared to native grasses, acts as an opportunistic colonizer of bare and disturbed soils.