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, dense growth, and good disease resistance)
Hardiness Zones
Thrives in USDA Hardiness Zones 3 through 7. Excellent cold tolerance, surviving sub-zero winter temperatures through winter dormancy. Susceptible to heat stress in deep southern climates.
About This Grass
Forms a dense, high-quality turf with a medium-fine texture and rich dark blue-green coloration. Height ranges from 1.5 to 2.5 inches when maintained as a lawn, but can grow up to 18-24 inches if 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, and the collar is broad and continuous.
Root System
Moderately deep fibrous root system combined with extensive underground rhizomes. Forms a very tough, dense sod. Moderate to slow establishment speed from seed, with a moderate tendency to form thatch under high fertilization.
Growing Information
Origin Region
Europe, northern Asia, and parts of the mountains of North Africa; widely cultivated and naturalized across North America, especially in the northern US and Canada.
Growth Habit
Rhizomatous, spreading underground via aggressive creeping rhizomes to form a dense, uniform turf mat.
Sunlight & Water Needs
Requires full sun (at least 6-8 hours daily) for best performance, with poor shade tolerance. Watering needs are moderate to high; enters summer dormancy during extended droughts but recovers well with irrigation. Prefers well-drained, fertile soils with a pH of 6.0 to 7.0.
Mowing & Maintenance
Ideal mowing height is 2.0 to 3.5 inches. Mowing frequency is high during peak spring and fall growth periods. Fertilization requirement is medium to high (3-5 lbs N per 1000 sq ft per year). Regular dethatching and core aeration are recommended due to sod density. Medium-High maintenance level.
Special Characteristics
High wear and traffic tolerance due to aggressive self-repairing rhizomes. Susceptible to certain diseases like dollar spot, summer patch, and leaf spot. Moderate drought dormancy capability. Excellent erosion control and weed suppression.
Ecological Information
Introduced species in North America. Provides limited wildlife habitat mostly as a grazing source for herbivores. Excellent soil stabilization and water filtration capabilities due to dense sod formation. Frequently mixed with perennial ryegrass and fine fescues in cool-season lawn seed blends.