Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
AI-generated identification · may be incorrect
Grass Category
Lawn/Turf Grass, Sports Turf
Hardiness Zones
Thrives in USDA Hardiness Zones 3 through 7, extending into cooler parts of Zone 8. Excellent cold tolerance (survives extreme sub-zero winter temperatures), enters winter dormancy in cold regions, and goes into summer dormancy during excessive heat.
Grass Family
Poaceae, subfamily Pooideae
Variety / Cultivar
Midnight (known for dark blue-green color and excellent turf density)
About This Grass
Forms a lush, dense, dark blue-green turf with medium-fine texture. When unmowed, it can reach heights of 18 to 24 inches, but it is typically maintained at 1.5 to 2.5 inches. Produces open, pyramid-shaped panicle seed heads at maturity during late spring.
Blade Characteristics
Blades are medium-fine in width (2-4mm), flat to folded with distinct parallel veins and characteristic boat-shaped tips. Vernation is folded in the bud. Ligule is short and membranous, and auricles are absent.
Root System
Features a fibrous, moderately deep root system accompanied by aggressive rhizomes. Can form a dense, tough sod that exhibits moderate thatch-forming tendencies. Slow to establish from seed, but recovers well from damage via rhizomatous spread.
Growing Information
Origin Region
Europe and Northern Asia; widely naturalized and cultivated across North America and temperate regions worldwide
Growth Habit
Rhizomatous, spreading extensively via underground stems to form a dense, uniform sod
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily) for optimal growth, with poor shade tolerance. Moderate to high water needs; goes dormant and turns brown during extended summer droughts, but revives when moisture returns. Prefers well-drained, fertile soils with a pH of 6.0 to 7.0.
Mowing & Maintenance
Ideal mowing height ranges from 1.5 to 2.5 inches. Requires frequent mowing during peak spring and fall growth periods. Fertilization needs are medium to high (3-4 lbs N per 1000 sq ft per year). Requires periodic dethatching and core aeration due to dense sod and thatch accumulation. Maintenance level is medium-high.
Special Characteristics
Excellent traffic and wear tolerance due to aggressive spreading rhizomes. Moderate to good disease resistance, though susceptible to dollar spot, rust, and summer patch. Low shade and salt tolerance. Outstanding ability to self-repair and crowd out weeds when healthy.
Ecological Information
Introduced species in North America. Provides good soil stabilization and erosion control due to its dense root and rhizome matrix. Commonly blended with perennial ryegrass and fine or tall fescues in turf seed mixes to improve establishment speed and disease resistance.