Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, subfamily Pooideae, tribe Poeae
Grass Category
Lawn/Turf Grass, Sports Turf, Golf Course Grass
Variety / Cultivar
General species type / 'Midnight' type common in blends
Hardiness Zones
Thrives in USDA Hardiness Zones 3 through 7. Excellent cold tolerance, but struggles with extreme summer heat unless irrigated.
About This Grass
Forms a rich, dark green to blue-green, dense turf with a fine to medium texture. Unmowed height can reach 18 to 24 inches, but maintained lawn height is typically 1.5 to 2.5 inches. Exhibits moderate to slow establishment from seed but spreads well once established.
Blade Characteristics
Fine to medium width (2-4mm), flat to folded with prominent parallel veins and characteristic boat-shaped tips. Vernation is folded in the bud. Ligule is short and membranous, auricles are absent.
Root System
Moderate depth (6-12 inches) fibrous root system with extensive underground rhizomes that form a very tough, dense sod. Can be prone to moderate thatch accumulation under high maintenance.
Growing Information
Origin Region
Europe, northern Asia, and parts of the mountains in the western North America
Growth Habit
Rhizomatous, spreading underground via aggressive underground stems to form a dense turf
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily) for optimal growth, though some cultivars offer moderate shade tolerance. High water requirements to maintain green color during summer heat; goes dormant during severe drought.
Mowing & Maintenance
Ideal mowing height ranges from 2.0 to 3.5 inches. Requires medium-high maintenance including regular fertilization (2-4 lbs N per 1000 sq ft annually), periodic dethatching, and reliable irrigation.
Special Characteristics
High traffic and wear tolerance due to aggressive rhizomatous recovery, excellent cold hardiness, and good winter color retention in milder cool-season zones. Moderate susceptibility to certain diseases like dollar spot and leaf spot.
Ecological Information
Widely naturalized across North America. Provides good soil stabilization and erosion control through its dense root and rhizome network. Commonly mixed with perennial ryegrass and fine fescues for lawns.