Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, subfamily Pooideae
Grass Category
Lawn/Turf Grass
Variety / Cultivar
Midnight (typical dark green, dense turf variety)
Hardiness Zones
USDA Hardiness Zones 3-7. Excellent cold tolerance, but struggles with extreme summer heat unless irrigated.
About This Grass
Forms a dense, lush turf with a rich green to medium-dark green color. Height ranges from 1.5 to 2.5 inches when maintained as a lawn, but can grow up to 18-24 inches if left unmowed, producing open, pyramidal panicle seed heads.
Blade Characteristics
Blades are medium-fine (2-4mm wide), 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
Moderately deep fibrous root system combined with extensive underground rhizomes. Establishes relatively slowly from seed, but forms a very tough, dense sod once mature.
Growing Information
Origin Region
Europe and Northern Asia; widely cultivated across North America, especially in the northern US and Canada
Growth Habit
Aggressively rhizomatous, forming a dense, uniform sod
Sunlight & Water Needs
Requires full sun (at least 6-8 hours daily), though some cultivars have moderate shade tolerance. High watering needs during dry spells to stay green, but goes into summer dormancy under severe drought, recovering when moisture returns. Prefers well-drained, fertile soils with a pH of 6.0-7.0.
Mowing & Maintenance
Ideal mowing height is 2.0 to 3.0 inches. Requires regular weekly mowing during the active growing season. High fertilizer requirements (3-4 lbs N per 1000 sq ft annually). Medium-high maintenance level.
Special Characteristics
Exceptional wear tolerance and self-repairing capability via rhizomes. Moderate shade tolerance depending on cultivar. Good recovery from dormancy, excellent cold winter color retention in milder zones, and forms a thick carpet that naturally resists weeds.
Ecological Information
Introduced species in North America. Provides good soil stabilization, erosion control, and turf cover. Often blended with Perennial Ryegrass and Fine Fescues to improve disease resistance and establishment speed.