Kentucky Bluegrass
Poa pratensis · Cool-season Performance, Perennial, C3 pathway
Grass Family
Poaceae, Subfamily Pooideae, Tribe Poeae
Grass Category
Lawn/Turf Grass, Sports Turf, and Pasture Grass
Variety / Cultivar
Indeterminate; common/unimproved variety typically found in mixed turf environments
Hardiness Zones
USDA Zones 2-7. Excellent cold tolerance but poor heat tolerance, often going dormant or thinning out in southern transition zones.
About This Grass
A medium-textured grass with a distinctive dark green to blue-green color. It forms a dense, carpet-like turf. In the provided image, the grass shows significant dormant or dead brown blades, likely due to heat stress or drought, mixed with active green growth and broadleaf weeds like clover.
Blade Characteristics
Blade width is medium (2-4mm). Tips are uniquely boat-shaped (keeled). Vernation is folded in the bud. Ligule is short and membranous; auricles are absent. The upper leaf surface is smooth with a distinct 'twin' mid-vein.
Root System
Moderately shallow fibrous root system supported by an extensive network of rhizomes. High thatch tendency. Establishment is slow compared to ryegrass but results in a very durable sod.
Growing Information
Origin Region
Native to Europe, North Asia, and the mountains of Morocco and Algeria; widely adapted to temperate climates of North America.
Growth Habit
Rhizomatous (spreading via underground stems). Forms a thick, dense sod by spreading laterally.
Sunlight & Water Needs
Prefers full sun (minimum 6-8 hours). Moderate to high water needs; will enter summer dormancy (turning brown as seen in image) during prolonged drought without irrigation. Prefers well-drained soil with pH 6.0-7.5.
Mowing & Maintenance
Recommended height of 2.0-3.5 inches. High maintenance level. Requires 2-4 lbs of Nitrogen per 1000 sq ft annually and regular dethatching/aeration due to rhizome growth.
Special Characteristics
Excellent wear tolerance and recovery due to rhizomes. Good disease resistance in modern cultivars, though susceptible to summer patch and necrotic ring spot. Highly valued for aesthetic 'golf course' appearance.
Ecological Information
Introduced species in North America. Provides good soil stabilization and erosion control. Often mixed with Perennial Ryegrass and Fine Fescue for ecological diversity and shade tolerance.