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 blend/cultivar (e.g., 'Midnight' type), known for dark green color and dense sod formation
Hardiness Zones
Thrives in USDA Hardiness Zones 3 through 7. Excellent cold tolerance, but struggles with extreme summer heat unless irrigated, making it less ideal for the deep southern transition zone without careful management.
About This Grass
Forms a lush, dense, medium-textured turf with a rich medium-to-dark green color. Unmowed height can reach 18 to 24 inches with open, pyramidal panicle seed heads, but is typically maintained at 1.5 to 2.5 inches. Exhibits moderate winter dormancy in freezing climates.
Blade Characteristics
Medium blade width (2-4 mm), flat to V-shaped with distinct parallel veins and characteristic boat-shaped tips. Vernation is folded in the bud. Features a short membranous ligule, no auricles, and a continuous collar region.
Root System
Moderately deep fibrous root system combined with aggressive rhizomes. Forms a dense sod with moderate thatch-forming tendencies. Slow to establish from seed, but offers excellent self-repairing wear recovery.
Growing Information
Origin Region
Europe and Northern Asia; widely naturalized and cultivated across North America and temperate regions worldwide
Growth Habit
Rhizomatous, spreading underground via extensive networks of slender rhizomes to form a dense, uniform turf mat
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily), though some cultivars offer moderate shade tolerance. High watering needs during dry spells to maintain green color, though it enters summer dormancy during severe drought. Prefers well-drained, fertile soils with a pH of 6.0 to 7.0.
Mowing & Maintenance
Ideal mowing height ranges from 2.0 to 3.5 inches. Requires regular mowing during active spring and fall growth periods. High fertilizer requirement (3-4 lbs N per 1000 sq ft annually). Regular dethatching and aeration are needed due to heavy sod and thatch buildup. High maintenance level.
Special Characteristics
High wear tolerance and exceptional self-repair capability due to rhizomes. Moderate disease susceptibility (prone to leaf spot, dollar spot, and summer patch). Good drought dormancy recovery. Excellent for home lawns, athletic fields, and golf course fairways.
Ecological Information
Introduced to North America by European settlers. Provides standard lawn ecosystem services including soil stabilization, carbon sequestration, and stormwater runoff reduction. Frequently blended with Perennial Ryegrass and Fine Fescue for improved disease resistance and rapid establishment.