Prostrate Knotweed
Polygonum aviculare · Summer Annual, C3/Dicot
Grass Family
Polygonaceae (Knotweed Family); Not a true grass (Poaceae)
Grass Category
Broadleaf Weed (often mistaken for grass or mats)
Variety / Cultivar
Common wild type
Hardiness Zones
USDA Zones 3-10; thrives in summer heat and dies back after the first hard frost.
About This Grass
A low-growing, wiry broadleaf plant that mimics grass in mowed turf. It forms dense, circular mats of bluish-green foliage with small, inconspicuous white-to-pink flowers at the leaf axils.
Blade Characteristics
Leaves are alternate, simple, narrow-elliptic to linear (1-3cm long), bluish-green; feature a thin, papery sheath (ochrea) at each swollen stem node; lack veins/auricles seen in grasses.
Root System
Deep, thin taproot that can penetrate compacted soils; creates a strong anchor but does not spread via rhizomes.
Growing Information
Origin Region
Native to Europe, naturalized throughout North America and temperate regions worldwide
Growth Habit
Prostrate, mat-forming; stems radiate from a central taproot
Sunlight & Water Needs
Full sun to partial shade; highly drought-tolerant; excels in dry, compacted soils where turf grasses fail.
Mowing & Maintenance
Extremely low-mowing tolerant (survives at heights <1 inch); requires pre-emergent herbicide in early spring; manual pulling or broadleaf herbicides like 2,4-D for control.
Special Characteristics
Exceptional resistance to foot traffic and soil compaction; excellent salt tolerance; often the first weed to appear on trodden paths or sports field sidelines.
Ecological Information
Introduced species; provide seeds for small birds (finches, sparrows); indicator plant for high-traffic or severely compacted soil areas.