Annual Bluegrass
Poa annua · Cool-season annual (occasionally short-lived perennial), C3
Grass Family
Poaceae, subfamily Pooideae, tribe Poeae
Grass Category
Invasive/Weed Grass, Golf Course Grass (sometimes maintained as greens)
Variety / Cultivar
Common Poa annua (var. annua)
Hardiness Zones
USDA Zones 3-10; thrives in cool, moist spring/fall weather; often dies off or goes dormant in summer heat.
About This Grass
A low-growing, light green grass characterized by its prolific seed production. It often forms unsightly clumps in managed turf and has a distinct pale green color that contrasts with darker lawn grasses.
Blade Characteristics
Fine to medium width (2-3mm), soft and crinkled when young. Blades are flat with a distinct boat-shaped tip, folded vernation, and a long, silvery, membranous ligule. No auricles.
Root System
Shallow fibrous root system; lacks rhizomes or stolons. Rapid establishment from seed but very low drought tolerance due to shallow roots.
Growing Information
Origin Region
Native to Europe and Asia; naturalized worldwide in temperate climates
Growth Habit
Bunch-type/clump-forming with a somewhat spreading or sprawling habit; can form small mats
Sunlight & Water Needs
Full sun to partial shade; prefers moist to over-watered soils and high humidity. Highly opportunistic in compacted or poorly drained areas.
Mowing & Maintenance
Extremely low mowing tolerance (can survive and set seed even at 0.1 inch). High maintenance as a weed to eradicate; requires pre-emergent herbicides and careful water management.
Special Characteristics
Prodigious seed producer (thousands per plant); high shade tolerance; low wear tolerance but high recovery rate via reseeding; very poor heat and drought tolerance.
Ecological Information
Introduced/Invasive; provides minor forage for some birds but generally considered a nuisance weed that outcompetes desired turf species in high-moisture environments.