Prostrate Knotweed (Mixed with Tall Fescue)
Polygonum aviculare (in a turf of Festuca arundinacea) · Summer Annual Broadleaf (Polygonum); Perennial Cool-season C3 (Festuca)
Grass Family
Polygonaceae (Knotweed family); note: background grass is Poaceae (Pooideae)
Grass Category
Invasive/Weed (Knotweed) and Lawn/Turf Grass (Fescue)
Variety / Cultivar
Common wild-type prostrate knotweed; background fescue appears to be a Turf-Type Tall Fescue (TTTF) blend
Hardiness Zones
USDA Zones 3-10; Knotweed is highly heat tolerant and germinates in early spring; Fescue thrives in Zones 4-7 but struggles in extreme southern heat.
About This Grass
The image shows a low-growing, lime-green carpet of prostrate knotweed infiltrating a darker green, medium-textured turf. The knotweed forms dense, flat mats that choke out the primary grass. At maturity, knotweed has tiny white-to-pink flowers in leaf axils. The fescue provides a backdrop of upright, dark green blades.
Blade Characteristics
Knotweed: Not a true grass; small, elliptical, alternate leaves (1-3cm long) with a papery sheath (ocrea) at the nodes. Fescue: Flat blades, 4-8mm wide, prominent veins on top, smooth underside, pointed tips, rolled vernation, no auricles, short membranous ligule.
Root System
Knotweed: Deep, tough taproot allowing survival in compacted soil; Fescue: Deep fibrous root system with high drought tolerance for a cool-season grass; low thatch tendency.
Growing Information
Origin Region
Knotweed is native to Eurasia but naturalized globally; Fescue is native to Europe and North Africa, adapted to the Transition Zone
Growth Habit
Knotweed: Prostrate, mat-forming, branched from taproot; Fescue: Bunch-type, clump-forming with limited short rhizomes
Sunlight & Water Needs
Full sun to partial shade; Knotweed thrives in dry, compacted soils where turf fails. Fescue requires 4-6 hours sun and 1 inch of water per week.
Mowing & Maintenance
Knotweed: Tolerates extremely low mowing (under 1 inch); Fescue: Ideal height 3-4 inches. High maintenance required to eradicate the knotweed through aeration and broadleaf herbicides.
Special Characteristics
Knotweed: Excellent traffic tolerance, indicator of soil compaction. Fescue: Excellent wear tolerance and better shade tolerance than Kentucky Bluegrass.
Ecological Information
Knotweed is considered a noxious weed in ornamental turf; its seeds provide food for songbirds but it outcompetes native flora in disturbed sites. Fescue provides soil stabilization and high-density ground cover.