Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, subfamily Pooideae
Grass Category
Lawn/Turf Grass, Sports Turf, Golf Course Grass
Variety / Cultivar
Standard turf-type cultivars (e.g., 'Midnight', 'Baron')
Hardiness Zones
USDA Hardiness Zones 3 to 7, excellent cold tolerance, moderate heat tolerance requiring irrigation in summer.
About This Grass
Forms a dense, medium-textured turf with rich medium to dark green or blue-green color. Mown height typically maintained at 1.5 to 2.5 inches, but can reach 18 to 24 inches if unmowed, producing open, pyramidal panicle seed heads.
Blade Characteristics
Blades are medium width (2-4mm), flat to folded with distinct parallel veins and characteristic boat-shaped (prow-shaped) tips. Vernation is folded in the bud. Ligule is short and membranous; auricles are absent.
Root System
Moderate depth with extensive fibrous roots and aggressive rhizomes. Prone to moderate thatch buildup under high fertilization. Medium-slow establishment speed from seed, but excellent long-term wear recovery via rhizomes.
Growing Information
Origin Region
Europe, northern Asia, and parts of the mountains of the western US; widely cultivated across temperate regions globally.
Growth Habit
Aggressively rhizomatous, spreading via underground stems to form a dense, uniform turf mat.
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily) for optimal performance; moderate to high water needs to maintain green color during summer; goes into summer dormancy if unwatered; prefers well-drained fertile soils with pH 6.0-7.0.
Mowing & Maintenance
Ideal mowing height is 2.0 to 3.0 inches. Requires frequent mowing during peak spring/fall growth. High fertilizer needs (3-4 lbs N per 1000 sq ft annually). Moderate to high maintenance level.
Special Characteristics
Exceptional wear tolerance and self-repairing capability due to rhizomes. Good cold tolerance and winter color retention in milder cool regions. Susceptible to certain diseases like dollar spot, leaf spot, and summer patch.
Ecological Information
Introduced species in North America. Provides good soil stabilization and erosion control due to dense root and rhizome matrix. Often blended with perennial ryegrass and fine fescues in northern lawn seed mixtures.