Japanese Stiltgrass
Microstegium vimineum · Warm-season, Annual, C4
Grass Family
Poaceae, subfamily Panicoideae
Grass Category
Invasive/Weed Grass
Variety / Cultivar
Wild type (No specific cultivated varieties)
Hardiness Zones
USDA Hardiness Zones 5 to 9; thrives in temperate to subtropical woodland understories and shaded turf edges.
About This Grass
An annual grass with delicate, sprawling stems growing up to 3 feet long. Features light green, lance-shaped leaves. Forms dense, choking monocultures in shaded, moist environments. Produces terminal and axillary spike-like racemes in late summer.
Blade Characteristics
Blades are short (1 to 3 inches long), relatively wide (5 to 15 mm), flat, pale green, lanceolate with an off-center silvery stripe of reflective hairs on the upper surface. Vernation is folded; ligule is a short membrane; auricles absent.
Root System
Shallow, fibrous root system with weak roots; easily pulls up from the soil. Establishes rapidly from seed and rooting stem nodes, creating a shallow interwoven mat that does not form a durable turf sod.
Growing Information
Origin Region
Native to Asia (China, Japan, Korea, India, Malaysia); naturalized extensively in the eastern United States
Growth Habit
Stoloniferous, forming dense mats with weak branching stems that root at the nodes
Sunlight & Water Needs
Shade tolerant to partial sun, thrives in moist soils and disturbed shady areas. Low drought tolerance; susceptible to wilting in dry, exposed conditions. Prefers acidic to neutral, moist soils.
Mowing & Maintenance
Low maintenance weed; easily controlled or suppressed by frequent low mowing which prevents seed production, though individual plants can survive and produce seeds below the mower height if left unchecked.
Special Characteristics
Low wear tolerance, highly invasive weed that crowds out native vegetation in forests and lawns. Spreads aggressively via prolific seed production and floating stems.
Ecological Information
Introduced invasive species in North America. Provides little to no positive wildlife value, alters soil chemistry, increases wildfire risk by creating dry thatch, and heavily degrades native forest understory ecosystems.