Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3
Grass Family
Poaceae, subfamily Pooideae, tribe Poeae
Grass Category
Lawn/Turf Grass
Variety / Cultivar
Common/Mixed Cultivars (resembles classic lawn varieties like Midnight or Baron)
Hardiness Zones
USDA Zones 2-7; excellent cold tolerance but enters summer dormancy in high heat without irrigation.
About This Grass
A medium-textured, high-density residential turf grass. It exhibits a dark blue-green color when healthy, turning dormant and straw-colored during extreme heat or drought (as visible in the necrotic patches of the image). It produces small, panicle-type seed heads if left unmowed.
Blade Characteristics
Blade width is medium (2-4mm). The most defining feature is the boat-shaped leaf tip (shaped like the bow of a canoe). Vernation is folded in the bud; two prominent translucent lines (twin midribs) are often seen along the center of the leaf. Ligule is short and membranous; auricles are absent.
Root System
Moderately shallow fibrous root system supported by a network of rhizomes. High thatch-forming tendency but excellent sod-forming capability and moderate wear recovery.
Growing Information
Origin Region
Native to Europe, Northern Asia, and the mountains of Morocco and Algeria; highly adapted to cool-humid climates of North America
Growth Habit
Rhizomatous (underground spreading creeping stems); forms a dense, strong sod
Sunlight & Water Needs
Prefers Full Sun (6+ hours); moderate to high water requirements. Low shade tolerance. Prefers well-drained, fertile soil with a pH of 6.0 to 7.5.
Mowing & Maintenance
Ideal height is 2.0 to 3.5 inches. High maintenance level; requires regular fertilization (3-5 lbs N per 1000 sq ft per year) and periodic dethatching/core aeration.
Special Characteristics
Excellent traffic tolerance and recovery due to rhizomes. Susceptible to Leaf Spot, Summer Patch, and Necrotic Ring Spot (the latter potentially explaining the circular dead patches seen in the image).
Ecological Information
Introduced and naturalized in North America. Provides soil stabilization and filtration. Not considered highly invasive in managed landscapes but can dominate native grasslands in specific cool-temperate regions.