Annual Bluegrass
Poa annua · Cool-season annual (some perennial biotypes), C3, transition zone adaptivity
Grass Family
Poaceae, Pooideae, Poeae
Grass Category
Invasive/Weed Grass, occasionally Golf Course putting green turf
Variety / Cultivar
Common Poa annua
Hardiness Zones
USDA Zones 3-10; excellent cold tolerance but poor heat tolerance; typically dies off or goes dormant in hot summer months.
About This Grass
Low-growing, light green grass forming small tufts. Prolific seed production even at low mowing heights. Texture is soft; color is notably lighter/yellow-green compared to turf species like Kentucky Bluegrass.
Blade Characteristics
Fine to medium width (2-3mm), flat or slightly folded, smooth; tip is distinctly boat-shaped; vernation is folded; ligule is long, membranous, and white (0.5-3mm); auricles are absent.
Root System
Shallow fibrous root system; low thatch tendency but high plant density; lacks heat or drought-hardy roots; very fast establishment from seed.
Growing Information
Origin Region
Originating in Europe, now naturalized worldwide in temperate climates
Growth Habit
Bunch-type to low-mounded; can produce short stolons in some biotypes; aggressive spreader
Sunlight & Water Needs
Full sun to heavy shade (very shade tolerant); high water needs; poor drought tolerance; prefers moist, compact, high-nitrogen soils.
Mowing & Maintenance
Ideal height 0.5-2 inches (can survive at 0.1 inch on golf greens); high maintenance if managed as turf; requires frequent irrigation and fungicide.
Special Characteristics
Extremely high seed production; can produce seeds just days after mowing; poor traffic tolerance when stressed; highly susceptible to Pythium and Dollar Spot.
Ecological Information
Considered an invasive weed in most managed turf landscapes; provides minor forage for small birds but generally reduces biodiversity in native meadows.