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
Midnight (known for dark blue-green color, excellent density, and disease resistance)
Hardiness Zones
USDA Hardiness Zones 3 to 7; excellent cold tolerance; goes into winter dormancy in colder climates; can struggle in extreme summer heat of the deep southern transition zone
About This Grass
Forms a dense, high-quality turf with a medium texture and a rich dark green to blue-green color. Mowed height is typically maintained between 2 to 3.5 inches, while unmowed growth can reach 18 to 24 inches with pyramidal panicle seed heads.
Blade Characteristics
Medium blade width (2-4mm), folded in the bud (vernation), distinctive boat-shaped tips, prominent parallel veins with a tramline effect (two clear parallel lines alongside the midrib), membranous ligule, and absent auricles
Root System
Moderate to deep fibrous root system combined with extensive underground rhizomes; moderate establishment speed from seed; forms a dense thatch layer if over-fertilized; excellent wear recovery due to spreading rhizomes
Growing Information
Origin Region
Native to Europe, Northern Asia, and parts of North America; widely cultivated throughout temperate regions worldwide
Growth Habit
Rhizomatous, spreading underground via aggressive underground stems to form a dense, uniform sod
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily); medium to high watering needs; moderate drought tolerance entering summer dormancy during extended dry periods; prefers well-drained fertile soils with a pH of 6.0 to 7.0
Mowing & Maintenance
Ideal mowing height ranges from 2.0 to 3.0 inches; requires regular mowing during peak spring and fall growth; high maintenance level needing 3-4 lbs of nitrogen per 1000 sq ft annually, regular aeration, and periodic dethatching
Special Characteristics
Exceptional wear tolerance and self-repairing capability via rhizomes; moderate shade tolerance; susceptible to diseases like summer patch, dollar spot, and leaf spot if mismanaged; outstanding winter color retention compared to warm-season grasses
Ecological Information
Widely naturalized throughout North America; provides good soil stabilization and erosion control; commonly blended with Perennial Ryegrass and Fine Fescues to improve turf resilience and disease resistance