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
Standard turf-type cultivars (e.g., 'Midnight', 'America')
Hardiness Zones
USDA Hardiness Zones 3 through 7 (can extend to 8 in northern or higher elevation transition zones). Excellent cold tolerance; enters winter dormancy in freezing temperatures.
About This Grass
Forms a dense, high-quality turf with a medium-fine texture. Rich dark green to blue-green color. Reaches 18 to 24 inches if left unmowed, but maintained at 2 to 3 inches. Produces open, pyramidal panicle seed heads at maturity.
Blade Characteristics
Blades are medium-width (3-4mm), flat or folded, with distinct boat-shaped tips and prominent parallel veins giving a railroad-track appearance. Vernation is folded in the bud. Ligule is short and membranous; auricles are absent.
Root System
Moderately deep fibrous root system combined with extensive rhizomes. Tends to build up moderate thatch if over-fertilized. Slow to germinate and establish, but forms extremely tough, dense sod with excellent wear recovery.
Growing Information
Origin Region
Europe, Northern Asia, and mountainous parts of the US; widely naturalized and cultivated across cool, temperate regions worldwide
Growth Habit
Rhizomatous, spreading underground via aggressive creeping rhizomes to form a dense, uniform sod
Sunlight & Water Needs
Requires full sun (at least 6-8 hours daily), though some newer cultivars have moderate shade tolerance. High watering needs to maintain green color during summer; goes dormant (turns brown) during severe drought and recovers upon receiving moisture. Prefers well-drained, fertile soils with a pH of 6.0 to 7.0.
Mowing & Maintenance
Ideal mowing height is 2.0 to 3.0 inches. Requires frequent mowing during peak spring growth. Fertilizer needs are moderate to high (2-4 lbs N per 1000 sq ft annually). Needs periodic dethatching and core aeration. Maintenance level is Medium-High.
Special Characteristics
Exceptional wear and traffic tolerance due to rhizomatous spreading. Good cold tolerance and excellent winter color retention in milder cool-season zones. Susceptible to certain diseases like dollar spot, summer patch, and leaf spot under high humidity and stress.
Ecological Information
Introduced species in North America. Provides good soil stabilization and erosion control due to dense turf and rhizomes. Frequently blended with Perennial Ryegrass and Fine Fescues in cool-season lawn seed mixes.