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 cultivar (e.g., 'Midnight', 'Baron')
Hardiness Zones
USDA Hardiness Zones 3 through 7; excellent cold tolerance, moderate heat tolerance, struggles in extreme southern climates.
About This Grass
Forms an extremely dense, lush turf with a medium-fine texture and rich dark green to blue-green color. Unmowed height reaches 18 to 24 inches with panicle seed heads, but maintained turf is kept at 1.5 to 2.5 inches. Prone to summer dormancy under severe heat and drought without adequate irrigation.
Blade Characteristics
Medium-fine blades (2-4mm width) with parallel sides, characteristic boat-shaped tips, folded vernation in the bud, prominent parallel veins giving a railroad-track appearance, membranous ligule, and absent auricles.
Root System
Moderately deep fibrous root system combined with extensive underground rhizomes. Moderate establishment speed from seed, forms a very dense sod with a moderate to high tendency to develop thatch over time.
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 aggressive creeping rhizomes to form a dense sod
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours of direct sunlight) with low shade tolerance. High water needs to maintain green growth during peak summer; enters drought dormancy if unwatered. Prefers well-drained fertile soils with a pH of 6.0 to 7.0.
Mowing & Maintenance
Maintained at 1.5 to 2.5 inches height with regular mowing. High maintenance requirement, needing 3 to 4 lbs of nitrogen per 1,000 sq ft annually, regular irrigation, annual aeration, and periodic dethatching.
Special Characteristics
High traffic and wear tolerance with excellent self-repairing capability via rhizomes. Good cold tolerance and winter dormancy. Moderate disease susceptibility (e.g., leaf spot, dollar spot, summer patch). Excellent weed-crowding ability.
Ecological Information
Introduced species in North America. Provides good soil stabilization and erosion control due to dense root and rhizome network. Commonly mixed with Perennial Ryegrass and Fine Fescues for turf blends.