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 commercial blend (e.g., 'Midnight', 'Baron')
Hardiness Zones
USDA Hardiness Zones 3-7. Excellent cold tolerance, but struggles with extreme summer heat and humidity in the deep southern US transition zone.
About This Grass
Forms a dense, high-quality turf with a medium-fine texture and rich medium to dark green color. Reaches up to 18-24 inches if unmoved, but maintained at 1.5-2.5 inches. Produces open, pyramid-shaped panicle seed heads at maturity.
Blade Characteristics
Medium-fine width (2-3mm), flat to folded with prominent parallel veins and distinctive boat-shaped tips. Vernation is folded in the bud. Ligule is short and membranous; auricles are absent.
Root System
Moderate depth (6-12 inches) with a fibrous root system and aggressive rhizomes. Tends to build up thatch over time if over-fertilized. Moderate establishment speed from seed, but forms exceptionally tough sod once mature.
Growing Information
Origin Region
Europe and Northern Asia; widely naturalized and cultivated across North America and temperate regions worldwide
Growth Habit
Rhizomatous, spreading extensively via underground runners to form a dense, uniform sod
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily); poor shade tolerance. High water needs to maintain green color during summer droughts; goes into summer dormancy under severe drought but recovers well when moisture returns. Prefers well-drained, fertile loams with a pH of 6.0-7.0.
Mowing & Maintenance
Mow at 1.5 to 2.5 inches. Requires frequent mowing during peak spring/fall growth. High fertilization needs (3-5 lbs N per 1000 sq ft annually). Moderate to high maintenance level requiring regular aeration and occasional dethatching.
Special Characteristics
Exceptional wear tolerance and self-repairing capability via rhizomes. Good cold hardiness and winter color retention in milder climates. Susceptible to diseases like leaf spot, dollar spot, and summer patch under stress.
Ecological Information
Introduced species in North America. Used extensively in turf mixes with perennial ryegrass and fescues. Provides standard lawn ecosystem services like soil stabilization, dust reduction, and temperature moderation, though limited wildlife forage value compared to native grasses.