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
Standard lawn cultivars (e.g., 'Midnight', 'Bewitched'), known for dark green color and disease resistance
Hardiness Zones
USDA Hardiness Zones 3 to 7, tolerates cold winters very well but struggles with extreme summer heat and humidity characteristic of the deep southern transition zone.
About This Grass
Forms a dense, fine to medium-textured turf with an upright growth habit. Reaches 18 to 24 inches if unmoved, but maintained at 1.5 to 2.5 inches. Color ranges from medium to dark green, sometimes with a bluish tint. Produces open, pyramidal panicle seed heads at maturity.
Blade Characteristics
Medium width (2-4mm), folded in the bud (vernation), with parallel sides and distinct boat-shaped tips. Prominent parallel veins on the upper surface. Ligule is short and membranous; auricles are absent.
Root System
Moderately deep fibrous root system with extensive underground rhizomes. Tends to form moderate thatch under high fertilization and watering. Establishes slowly from seed, but spreads well once established to form a tough sod.
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, uniform turf
Sunlight & Water Needs
Requires full sun (at least 6-8 hours daily); poor shade tolerance. High water needs to maintain green color during summer; goes into summer dormancy (turning brown) during severe drought but recovers well when moisture returns. 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/fall growth. High maintenance level requiring 2 to 4 lbs N per 1000 sq ft annually, regular irrigation, and occasional dethatching/aeration.
Special Characteristics
Excellent traffic and wear tolerance due to aggressive rhizomatous recovery. Good cold tolerance and winter color retention compared to warm-season grasses. Susceptible to certain diseases like dollar spot, summer patch, and leaf spot.
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 home lawns to improve disease resistance and establishment speed.