Annual Bluegrass
Poa annua · Cool-season, Annual (though some subspecies act as short-lived perennials), C3
Grass Family
Poaceae, Subfamily Pooideae
Grass Category
Invasive/Weed Grass (commonly found in lawns, golf courses, and sports turf)
Variety / Cultivar
Common (Wild type); likely the biotype P. annua var. annua which is strictly annual and common in home lawns.
Hardiness Zones
USDA Zones 3-11; survives cold winters but usually collapses and turns brown during hot, dry summer months.
About This Grass
A low-growing, tufted grass that often stands out due to its lighter yellowish-green color compared to desired turf. It is most distinctive for its prolific seed production, often producing seed heads even at very low mowing heights.
Blade Characteristics
Blade width is medium (2-3mm); shape is flat or slightly folded; tip is distinctly 'boat-shaped' (characteristic of all Poa species); color is light green to yellowish-green; vernation is folded in the bud; ligule is long, white, and membranous.
Root System
Shallow, fibrous root system; sets seed quickly; low drought tolerance; does not form a strong sod and pull up easily.
Growing Information
Origin Region
Native to Europe; now naturalized worldwide in temperate climates, especially in moist, shaded, or compacted areas.
Growth Habit
Low-growing, bunch-type to slightly spreading via weak stolons; forms dense, light-green tufts that disrupt lawn uniformity.
Sunlight & Water Needs
Prefers partial to full sun but is highly shade tolerant; thrives in high-moisture, over-watered, or poorly drained soils; sensitive to heat and drought.
Mowing & Maintenance
High maintenance if trying to eradicate. It can survive mowing heights as low as 0.1 inch (on golf greens). For control, it requires pre-emergent herbicides and reduced irrigation in autumn.
Special Characteristics
Incredible seed production (up to 360 seeds per plant per year); highly competitive in compacted soils; low traffic tolerance; often the first grass to die in summer, leaving bare spots.
Ecological Information
Introduced/Invasive; provides minor food value for some small birds but is generally considered a nuisance in managed landscapes; tends to dominate areas with high nitrogen and excessive water.