Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, Subfamily Pooideae, Tribe Poeae
Grass Category
Lawn/Turf Grass, Pasture/Forage, Sports Turf
Variety / Cultivar
Common or 'Kentucky-31 type' (Mix/Naturalized variety)
Hardiness Zones
USDA Hardiness Zones 2-7; excellent cold tolerance; poor heat tolerance (struggles in Southern US); goes dormant in winter (turns brown/straw-colored in extreme cold).
About This Grass
A dense, low-growing grass with a rich green to dark green color. When unmowed, it reaches heights of 12-24 inches with open, pyramid-shaped panicle seed heads. Texture is fine to medium, and it forms a thick mat that recovers well from traffic.
Blade Characteristics
Blade width is medium (2-4mm); characteristic 'boat-shaped' (V-shaped) leaf tips; flat or folded shape; vernation is folded; ligule is very short (0.2-1.0mm) and membranous; auricles are absent; color ranges from light green to deep emerald; prominent central 'twin' veins.
Root System
Moderately shallow fibrous root system with extensive horizontal rhizomes; forms a dense, durable sod; moderate thatch tendency; relatively slow establishment speed from seed.
Growing Information
Origin Region
Native to Europe, North Asia, and Northern Africa; well-adapted throughout North America in temperate regions
Growth Habit
Rhizomatous (spreading underground via rhizomes), forming a dense, uniform sod; slow to moderate spread rate
Sunlight & Water Needs
Prefers Full Sun (6+ hours); moderate shade tolerance compared to fescues; high water needs (1-1.5 inches per week); enters dormancy during severe drought; prefers well-drained loamy soil with pH 6.0-7.0.
Mowing & Maintenance
Ideal height 2.0-3.0 inches; weekly frequency; requires 3-5 lbs N per 1000 sq ft annually; high maintenance; requires periodic dethatching and core aeration to manage sod density.
Special Characteristics
Excellent wear tolerance and recovery due to rhizomes; susceptible to leaf spot, melting out, and necrotic ring spot; moderate salt tolerance; high ability to crowd out weeds once established.
Ecological Information
Introduced/Naturalized in North America; high value for erosion control on slopes; provides food for various moth larvae and cover for small mammals; often mixed with Perennial Ryegrass or Fine Fescue for genetic diversity.