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 dark blue-green color, dense growth, and good disease resistance)
Hardiness Zones
Thrives in USDA Hardiness Zones 3 through 7. Excellent cold tolerance, moderate heat tolerance (struggles in deep southern summer heat without irrigation), widely used in the northern transition zone often blended with tall fescue.
About This Grass
Forms a dense, high-quality turf with a rich blue-green to dark green color. Maintains upright growth with fine to medium texture. Unmowed height can reach 18 to 24 inches, but typically maintained at 1.5 to 2.5 inches. Produces open, pyramid-shaped panicle seed heads at maturity in late spring.
Blade Characteristics
Fine to medium width (2-4mm), flat to folded shape with distinctive boat-shaped tips and prominent parallel veins giving a railroad-track appearance. Vernation is folded in the bud. Ligule is short and membranous; auricles are absent.
Root System
Moderate rooting depth (fibrous with extensive branching rhizomes), forms a tough, dense sod. Tends to build up moderate thatch under high fertilization. Slow to germinate and establish from seed, but excellent recovery from wear via rhizomes.
Growing Information
Origin Region
Europe, northern Asia, and mountainous regions of North America; widely cultivated across northern and transitional regions of the United States and Canada
Growth Habit
Rhizomatous, spreading underground via aggressive creeping rhizomes to form a dense, uniform turf mat
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily), moderate to high water needs for optimal appearance, moderate drought tolerance (enters dormancy during severe summer drought), 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 3-5 lbs N per 1000 sq ft annually, regular irrigation, annual aeration, and dethatching as needed.
Special Characteristics
Good traffic and wear tolerance due to aggressive rhizomatous recovery. Moderate shade tolerance (best in full sun). Susceptible to certain diseases like dollar spot, leaf spot, and summer patch under stress. Excellent winter color retention in cooler climates.
Ecological Information
Introduced species in North America. Provides good soil stabilization and erosion control through dense sod formation. Frequently blended with perennial ryegrass and fine fescues in commercial turf seed mixes to improve establishment speed and disease resistance.