Japanese Stiltgrass (Microstegium vimineum)
Microstegium vimineum · Warm-season Annual, C4 photosynthetic pathway
Grass Family
Poaceae, Panicoideae, tribe Andropogoneae
Grass Category
Highly Invasive Weed / Environmental Weed
Variety / Cultivar
None (Wild species)
Hardiness Zones
USDA Zones 4-11. Extremely adaptable. Dies back completely after the first hard frost but leaves a dense seed bank for spring germination.
About This Grass
A delicate-looking, sprawling annual grass that forms dense, carpet-like mats. Reaches heights of 1-3 feet if unmowed, but adapts to low heights. Pale to lime green in color, turning reddish-purple in autumn. Dense foliage with a bamboo-like appearance.
Blade Characteristics
Short, lance-shaped blades (1.3-8 cm long). Pointed tips. Pale green with a distinct, off-center silvery midrib (reflective line). Rolled vernation. Ligule is a short membrane; auricles absent. Thin, papery texture.
Root System
Shallow, fibrous root system. High thatch-forming potential due to matting. Establishes rapidly from seed bank or rooting stem nodes. Poor drought tolerance compared to perennial turf.
Growing Information
Origin Region
Native to East Asia (China, India, Japan, Korea); naturalized and highly invasive in Eastern United States
Growth Habit
Stoloniferous; sprawling, mat-forming habit. Spreads via seeds and rooting at nodes (decumbent stems).
Sunlight & Water Needs
Highly shade-tolerant (thrives in 5% sunlight) but grows in full sun. Prefers moist to wet soils, acidic to neutral pH. High water requirement; prone to wilting in dry conditions.
Mowing & Maintenance
Maintenance is usually for control rather than cultivation. Can survive mowing at 2 inches. Regular mowing prevents seed production. Low fertilization needs as it outcompetes native flora in low-nutrient soils.
Special Characteristics
Extreme shade tolerance; salt-sensitive; allelopathic (alters soil chemistry to inhibit other plants); high seed production (up to 1,000 per plant). Does not tolerate heavy traffic well.
Ecological Information
Introduced/Invasive status. Displaces native groundcover and suppresses tree seedling regeneration. Minimal wildlife value as most herbivores (deer) find it unpalatable. Often found with companion weeds like Ground Ivy or invasive Honeysuckle.