Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3
Grass Family
Poaceae, subfamily Pooideae, tribe Poeae
Grass Category
Lawn/Turf Grass, Sports Turf, Golf Course Grass
Variety / Cultivar
Midnight (exemplary cultivar)
Hardiness Zones
USDA Hardiness Zones 2 through 7. High cold tolerance; excellent frost resistance but poor heat tolerance above 90°F.
About This Grass
A dark green, dense turfgrass that provides a lush, carpet-like appearance. It grows 6-12 inches if unmowed, producing open, pyramidal panicle seed heads. It enters dormancy in extreme heat and turns brown in winter frost.
Blade Characteristics
Fine to medium width (2-3mm); V-shaped or flat; boat-shaped (keeled) tips; dark green to blue-green color. Vernation is folded in the bud. Ligule is short and membranous; auricles are absent.
Root System
Moderately shallow fibrous roots with extensive rhizomes. High thatch-forming tendency. Establishment is slow (21-28 days to germinate) but forms a very stable, dense sod.
Growing Information
Origin Region
Europe, Northern Asia, and North Africa; widely naturalized in North America and temperate regions worldwide
Growth Habit
Rhizomatous (spreading via underground stems), forming a dense, self-repairing sod
Sunlight & Water Needs
Full Sun (6-8 hours minimum) to slight shade. High water needs; requires 1-1.5 inches of water per week. Moderate drought tolerance (goes dormant to survive) and prefers neutral soil (pH 6.0-7.0).
Mowing & Maintenance
Ideal height: 2.0 to 3.5 inches. High maintenance level; requires 3-5 lbs of Nitrogen per 1000 sq ft annually and regular core aeration to manage thatch.
Special Characteristics
Excellent wear tolerance and recovery due to rhizomes. Susceptible to summer patch, necrotic ring spot, and dollar spot. High salt sensitivity. Widely used for professional sports fields and premium home lawns.
Ecological Information
Introduced/Naturalized in North America. Provides limited food for grazing wildlife; excellent for soil erosion control through tight sod formation. Often used in mixes with Perennial Ryegrass and Fine Fescue.