Annual Bluegrass
Poa annua · Cool-season, Annual (though some biotypes act as short-lived perennials), C3
Grass Family
Poaceae, Subfamily Pooideae, Tribe Poeae
Grass Category
Invasive/Weed Grass, though often found on Golf Course Greens
Variety / Cultivar
Common Poa annua (wild type)
Hardiness Zones
USDA Zones 3-10; thrives in cool, moist spring/fall weather; often dies or goes dormant in summer heat.
About This Grass
A light green, low-growing grass with a prolific seed-producing habit. It has a soft texture and often stands out in dark green lawns due to its lighter yellowish-green color and abundant small, whitish panicle seed heads.
Blade Characteristics
Fine to medium width (2-3mm), soft, typically light green. Tip is boat-shaped. Vernation is folded in the bud. Ligule is membranous, long (1-3mm), and white; auricles are absent.
Root System
Shallow fibrous root system; lacks rhizomes or stolons (reproduces by seed). Very poor drought tolerance and easily pulled from the soil.
Growing Information
Origin Region
Native to Europe and Eurasia; naturalized globally in temperate climates
Growth Habit
Bunch-type to semi-prostrate; can form dense low-growing mats under low mowing heights
Sunlight & Water Needs
Prefers Full Sun to Partial Shade; requires frequent moisture and thrives in overwatered or compacted soils; poor drought tolerance.
Mowing & Maintenance
Mowing height can be as low as 0.125 inches (golf greens) to 3 inches (lawns). It is a prolific seeder even at low heights. High maintenance as a weed, requiring pre-emergent herbicides.
Special Characteristics
Extremely high seed production; can produce viable seeds only days after flowering. Very low wear tolerance and poor heat/drought recovery.
Ecological Information
Introduced and considered highly invasive in turfgrass systems. Provides minimal wildlife value and often outcompetes desirable turf in wet, shaded, or compacted areas.