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
Standard turf-type cultivars (such as 'Midnight' or 'Compact-Midnight' types known for deep dark green color and dense growth)
Hardiness Zones
Thrives in USDA Hardiness Zones 3 through 7. Excellent cold tolerance, goes dormant in extreme winter freezes, and can struggle with heat stress in the deep southern transition zones.
About This Grass
Forms a dense, high-quality turf with a medium-fine texture and rich dark green to blue-green color. Mowed height is typically maintained between 1.5 to 2.5 inches, while unmowed plants can reach 18 to 24 inches with open, pyramidal panicle seed heads.
Blade Characteristics
Medium-fine width (2-4mm), flat to folded in the bud with characteristic boat-shaped tips, prominent parallel veins, and a smooth texture. Ligule is short and membranous, auricles are absent, and the collar is broad and continuous.
Root System
Moderately deep fibrous root system complemented by strong underground rhizomes. Forms a very dense sod, has a moderate to slow establishment rate from seed, and exhibits medium thatch-forming tendencies.
Growing Information
Origin Region
Native to Europe, northern Asia, and parts of North America; widely cultivated throughout the northern United States, Canada, and cool-temperate regions globally
Growth Habit
Aggressively rhizomatous, forming a dense, tightly knit sod and turf mat
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily) for optimal growth, though some newer cultivars tolerate partial shade. High water needs during dry spells; enters summer dormancy under severe drought conditions.
Mowing & Maintenance
Mow at 1.5 to 2.5 inches. Requires regular, frequent mowing during peak growth, high fertilization (3-5 lbs N per 1000 sq ft annually), periodic dethatching, and core aeration. Maintenance level is considered High.
Special Characteristics
Excellent traffic and wear tolerance due to aggressive rhizomatous recovery. Good cold and winter tolerance. Moderate shade tolerance depending on the cultivar. Susceptible to certain diseases like dollar spot and summer patch if over-fertilized or over-watered.
Ecological Information
Widely naturalized and heavily used in residential and commercial turf. Provides basic soil stabilization and erosion control. Often blended with perennial ryegrass and fine fescues in northern lawn seed mixtures to balance establishment speed and disease resistance.