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 (referenced as a common high-quality cultivar)
Hardiness Zones
USDA Hardiness Zones 2-7; excellent cold tolerance but undergoes winter dormancy and summer semi-dormancy in high heat.
About This Grass
A dark green, high-density turf grass that forms a thick sod. It reaches 12-24 inches if unmowed, featuring open, spreading panicle seed heads. It enters dormancy during extreme heat or drought.
Blade Characteristics
Blade width is fine to medium (2-4mm). Features a distinct V-shape or folded appearance with a unique boat-shaped tip. Color is typically deep emerald to blue-green. Vernation is folded in the bud; ligule is short and membranous; auricles are absent.
Root System
Moderately shallow fibrous root system supported by an extensive network of rhizomes. High thatch-forming tendency; slow to establish from seed but excellent at self-repairing through sod expansion.
Growing Information
Origin Region
Europe and Northern Asia; widely adapted to cool, humid climates of North America
Growth Habit
Rhizomatous (spreading via underground stems), forming a dense, sod-forming mat
Sunlight & Water Needs
Full sun preferred (6+ hours); moderate shade tolerance depending on cultivar. High water requirements; requires 1-1.5 inches of water per week. Prefers well-drained, fertile soil with pH 6.0-7.0.
Mowing & Maintenance
Ideal height 2.0 to 3.5 inches. Requires frequent mowing and high fertilization (3-5 lbs N per 1000 sq ft annually). High maintenance level requiring regular aeration.
Special Characteristics
Exceptional wear recovery due to rhizomes, high density, and beautiful color. Susceptible to summer patch, necrotic ring spot, and dollar spot. Low salt tolerance.
Ecological Information
Introduced/Naturalized in North America. Provides soil stabilization and erosion control. Used in mixes with Perennial Ryegrass and Fine Fescue for genetic diversity and shade adaptation.