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
Standard turf-type blends (e.g., 'Midnight', 'America')
Hardiness Zones
USDA Hardiness Zones 3 to 7, thriving in northern cool-temperate climates. Excellent cold tolerance, but struggles with intense summer heat in the deep southern US unless heavily irrigated.
About This Grass
Forms a dense, fine-to-medium textured turf with rich dark to medium green color. Unmowed height reaches 18 to 24 inches with pyramidal panicle seed heads. Maintained lawn height typically 1.5 to 2.5 inches. Exhibits moderate to high density.
Blade Characteristics
Medium width (2-4mm), flat to folded shape with characteristic boat-shaped tips. Color ranges from medium to dark green. Vernation is folded in the bud. Ligule is short and membranous; auricles are absent.
Root System
Moderate depth fibrous root system with extensive underground rhizomes. Moderate thatch tendency under high fertility and irrigation. Slow to moderate establishment speed from seed, but forms exceptionally strong, durable sod once established.
Growing Information
Origin Region
Europe, Northern Asia, and mountainous regions of North America; widely cultivated across cool-temperate regions worldwide
Growth Habit
Aggressively rhizomatous, spreading underground to form a dense, uniform sod and tight turf mat
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily) though some cultivars show moderate shade tolerance. High water needs to maintain green color during summer drought; enters summer dormancy under severe drought stress. Prefers well-drained, fertile soils with pH 6.0-7.0.
Mowing & Maintenance
Ideal mowing height between 2.0 to 3.0 inches. Requires frequent mowing during active spring and fall growth. High maintenance level requiring regular fertilization (3-4 lbs N per 1000 sq ft annually), periodic dethatching, and core aeration.
Special Characteristics
Good wear tolerance and excellent self-repairing capability via rhizomes. Moderate disease susceptibility (e.g., dollar spot, leaf spot, summer patch). Poor shade tolerance compared to tall fescue. Good winter color retention in milder cool-season zones.
Ecological Information
Widely naturalized in North America. Provides good soil stabilization and erosion control due to dense rhizome network. Frequently blended with perennial ryegrass and fine fescues for home lawns and sports fields to improve disease and wear resilience.