Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, subfamily Pooideae, tribe Poeae
Grass Category
Lawn/Turf Grass, Sports Turf
Variety / Cultivar
Common or unspecified blend (e.g., 'Midnight' type)
Hardiness Zones
USDA Hardiness Zones 3 through 7 (can extend to Zone 8 with sufficient irrigation). Excellent cold tolerance, goes dormant in freezing winter conditions, moderate to low heat tolerance compared to warm-season grasses.
About This Grass
Forms a dense, fine to medium-textured turf with an upright growth habit. Natural un-mowed height reaches 18 to 24 inches, maintained typically at 1.5 to 2.5 inches. Color ranges from medium to dark green or blue-green during active growth seasons. Goes dormant and turns straw-colored or brown during extreme summer heat or winter cold. Displays open, pyramid-shaped panicle seed heads at maturity.
Blade Characteristics
Blades are medium width (2-4mm), flat to folded with distinct parallel veins and characteristic boat-shaped tips. Vernation is folded in the bud. Ligule is short and membranous. Auricles are absent. Collar region is narrow and continuous.
Root System
Moderate root depth (typically 4-6 inches, capable of deeper growth in ideal soils). Fibrous with extensive underground rhizomes. Moderate tendency to form thatch under high fertilization. Slow to medium establishment speed from seed, but recovers well from stress via rhizomes once established.
Growing Information
Origin Region
Europe and Northern Asia, widely naturalized and cultivated across North America and temperate regions worldwide; performs best in northern temperate climates.
Growth Habit
Rhizomatous, spreading underground via aggressive creeping rhizomes to form a dense, uniform turf mat.
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily), though some modern cultivars have moderate shade tolerance. High water requirements to maintain green color during summer; enters summer dormancy under drought conditions. Prefers well-drained, fertile soils with a pH between 6.0 and 7.0.
Mowing & Maintenance
Ideal mowing height is 1.5 to 2.5 inches. Requires frequent mowing during peak spring and fall growth periods. High maintenance level requiring regular fertilization (3-4 lbs N per 1000 sq ft per year), periodic dethatching and core aeration, and regular irrigation.
Special Characteristics
High wear and traffic tolerance due to aggressive rhizomatous spreading and strong recuperative potential. Moderate disease susceptibility (susceptible to dollar spot, leaf spot, summer patch). Good drought survival via dormancy but slow to green up after severe drought. Excellent erosion control.
Ecological Information
Introduced species in North America. Provides moderate wildlife value for foraging birds and small mammals. Excellent soil stabilization and erosion prevention capabilities due to dense sod formation. Frequently blended with Perennial Ryegrass and Fine Fescues for home lawns.