Annual Bluegrass
Poa annua · Cool-season annual or short-lived perennial, C3 pathway
Grass Family
Poaceae, Pooideae, Tribe Poeae
Grass Category
Invasive/Weed Grass, Turf Grass (high-maintenance putting greens)
Variety / Cultivar
Common Poa annua (often biennial or perennial biotypes like 'Poa annua f. reptans')
Hardiness Zones
USDA Zones 2-10. Excellent cold tolerance; survives under snow but enters dormancy or dies during extreme summer heat.
About This Grass
A light-green, low-growing grass with a somewhat tufted appearance. It is most distinctive for its prolific, white-to-light-green, branched seed heads that appear even at very low mowing heights.
Blade Characteristics
Fine to medium width (2-3mm), soft and crinkled/undulated texture, light green color. Tips are boat-shaped. Vernation is folded in the bud; ligules are long, white, and membranous; auricles are absent.
Root System
Very shallow, fibrous root system. High thatch-forming tendency under heavy fertilization. Rapid establishment from seed but poor drought resistance due to root depth.
Growing Information
Origin Region
Originating in Eurasia, now naturalized globally in temperate and subtropical regions
Growth Habit
Low-growing, clumping towards bunch-type, but can produce short stolons in perennial biotypes
Sunlight & Water Needs
Adapts to full sun to heavy shade. High water requirements; requires constant moisture and often wilts quickly in heat or drought.
Mowing & Maintenance
Ideal height varies from 0.1 inch (greens) to 3 inches. High maintenance as a weed; requires frequent mowing to remove seed heads and high nitrogen to maintain color.
Special Characteristics
Highly tolerant of compact soil and low mowing heights; prolific seed producer (up to 300 seeds per plant); poor heat and drought tolerance; susceptible to Pythium and Dollar Spot.
Ecological Information
Introduced/Invasive species. Provides minimal wildlife value; often outcompetes desirable turfgrass in wet, shady, or compacted areas. Commonly found alongside Perennial Ryegrass and Kentucky Bluegrass.