Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, subfamily Pooideae, tribe Poeae
Grass Category
Lawn/Turf Grass, Sports Turf
Variety / Cultivar
Midnight (known for deep blue-green color and high density)
Hardiness Zones
USDA Hardiness Zones 3 to 7, thrives in northern climates with cold winters and moderate summers. Excellent cold tolerance, goes dormant during extreme winter freezes.
About This Grass
Forms a dense, low-growing turf with fine to medium texture. Unmowed height reaches 18 to 24 inches, but maintained lawn height is typically 1.5 to 2.5 inches. Features a rich blue-green to dark green color, developing panicle seed heads at maturity.
Blade Characteristics
Fine to medium width (2-4mm), flat to V-shaped with distinctive boat-shaped tips. Folded in the bud (vernation). Smooth texture with parallel veins and prominent light-colored midrib lines. Ligule is short and membranous, auricles absent.
Root System
Moderately deep fibrous root system combined with strong underground rhizomes. Moderate establishment speed, creates a thick thatch layer over time, excellent sod-forming and self-repairing capabilities.
Growing Information
Origin Region
Native to Europe, northern Asia, and parts of North America; widely cultivated in cool-temperate regions worldwide
Growth Habit
Rhizomatous, spreading underground via aggressive creeping stems to form a dense, uniform sod
Sunlight & Water Needs
Requires full sun (minimum 6 hours daily) for optimal growth, though some shade tolerance exists. Moderate to high water needs; goes into summer dormancy under severe drought but recovers well.
Mowing & Maintenance
Ideal mowing height is 2.0 to 3.0 inches. Medium to high maintenance. Requires 3-4 lbs of nitrogen per 1,000 sq ft annually. Regular dethatching and core aeration recommended due to dense thatch production.
Special Characteristics
High traffic and wear tolerance due to aggressive rhizomatous recovery. Moderate disease susceptibility (e.g., leaf spot, dollar spot, summer patch). Poor shade tolerance compared to fescues. Excellent erosion control.
Ecological Information
Introduced species in North America widely naturalized. Provides ground cover and soil stabilization, reduces runoff, serves as a food source and habitat for various urban wildlife and insects.