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, Erosion Control
Variety / Cultivar
General species type, often blended with improved cultivars like 'Midnight' or 'Baronie'
Hardiness Zones
Thrives in USDA Hardiness Zones 3 through 7, highly cold-tolerant, struggles in extreme southern heat unless heavily irrigated, and goes dormant in freezing winter temperatures.
About This Grass
Forms a lush, dense turf with medium-fine texture and rich dark green to blue-green color. Mown height typically ranges from 1.5 to 2.5 inches, while unmowed growth can reach 18 to 24 inches with open, pyramidal panicle seed heads.
Blade Characteristics
Medium-fine blades (2-4mm wide) with distinctive boat-shaped tips, folded vernation in the bud, prominent parallel veins giving a railroad-track appearance on either side of the midrib, and a short membranous ligule with absent auricles.
Root System
Moderately deep fibrous root system combined with aggressive rhizomes, creating a very strong sod. Exhibits a moderate to high tendency to form thatch if over-fertilized, with slow to moderate establishment speed from seed.
Growing Information
Origin Region
Native to Europe, northern Asia, and parts of the mountains in North America; widely naturalized and cultivated across cool-temperate regions worldwide.
Growth Habit
Rhizomatous, spreading extensively via underground stems to form a dense, uniform sod with moderate to high density.
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily) for optimal growth, though some cultivars offer moderate shade tolerance. High water needs during dry spells; enters summer dormancy during severe heat and drought, recovering upon receiving moisture.
Mowing & Maintenance
Ideal mowing height is 2.0 to 3.0 inches. Requires regular mowing, moderate to high fertilization (2-4 lbs N per 1000 sq ft annually), periodic dethatching and aeration, and high overall maintenance level.
Special Characteristics
Excellent traffic and wear tolerance due to aggressive rhizomatous recovery, good cold tolerance, moderate disease susceptibility (e.g., dollar spot, leaf spot), poor deep shade tolerance, and superior ability to crowd out weeds when healthy.
Ecological Information
Widely introduced and naturalized across North America, provides good soil stabilization and erosion control, offers minor wildlife cover, and is frequently blended with Perennial Ryegrass and Fine Fescue for resilient turf lawns.