Kentucky Bluegrass
Poa pratensis · Cool-season (C3), Perennial
Grass Family
Poaceae, Subfamily Pooideae, Tribe Poeae
Grass Category
Lawn/Turf Grass
Variety / Cultivar
Common or unknown domestic cultivar (exhibits typical medium-green color and density for residential turf)
Hardiness Zones
USDA Zones 2-7; excellent cold tolerance; enters dormancy during extreme heat or prolonged drought; best suited for northern climates.
About This Grass
A dense, low-growing turf grass with a prominent emerald to dark green color. When unmowed, it produces panicle seed heads. In the image, it presents as a mowed lawn with moderate density, currently heavily infested with broadleaf weeds (likely Creeping Charlie or Violets).
Blade Characteristics
Fine to medium width (2-4mm); V-shaped or flat; featuring a distinct boat-shaped tip; folded vernation in the bud; two prominent 'racing stripe' lines on the midrib; no auricles; short membranous ligule.
Root System
Moderately shallow fibrous root system with extensive horizontal rhizomes; forms a thick sod and heavy thatch layer over time; slow to establish compared to ryegrass but provides excellent long-term stability.
Growing Information
Origin Region
Native to Europe, Northern Asia, and the mountains of Morocco and Algeria; highly adapted to temperate climates
Growth Habit
Rhizomatous (spreading via underground stems), forming a dense, self-repairing sod
Sunlight & Water Needs
Full sun preferred (6+ hours); moderate shade tolerance; requires consistent moisture (~1 inch of water per week) to avoid summer dormancy; prefers well-drained soil with pH 6.0–7.5.
Mowing & Maintenance
Recommended height: 2.5–3.5 inches; high maintenance; requires regular fertilization (3-4 lbs Nitrogen per 1000 sq ft/year) and periodic dethatching/core aeration to manage rhizome buildup.
Special Characteristics
Excellent wear tolerance and recovery due to rhizomes; susceptible to leaf spot, melting out, and necrotic ring spot; superior winter hardiness compared to most turf grasses.
Ecological Information
Introduced and naturalized in North America; provides forage for various lepidoptera larvae; excellent soil stabilizer for erosion control; can be invasive in native prairie ecosystems; often blended with Perennial Ryegrass or Fine Fescue.