Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, Subfamily Pooideae, Tribe Poeae
Grass Category
Lawn/Turf Grass
Variety / Cultivar
Generic or Common (e.g., 'Midnight' or 'Baron' typical of residential lawns)
Hardiness Zones
USDA Hardiness Zones 2-7; excellent cold tolerance; poor heat tolerance; goes dormant and brown during hot summer months or extreme winter cold.
About This Grass
A medium-textured, high-density turf grass known for its dark green to blue-green color. It reaches 12-24 inches when unmowed. The visible patches in the image show dormant or necrotic spots, likely due to Dollar Spot or Summer Patch disease, against a healthy dark green canopy.
Blade Characteristics
Fine to medium width (2-4mm); V-shaped or flat; distinctive boat-shaped (keeled) tip; dark green to blue-green; vernation is folded; ligule is short and membranous; auricles are absent.
Root System
Relatively shallow to moderate depth; highly rhizomatous, allowing for excellent sod formation and recovery from wear; tends to produce significant thatch if over-fertilized.
Growing Information
Origin Region
Europe, Northern Asia, and the mountains of Algeria and Morocco; naturalized throughout North America
Growth Habit
Rhizomatous (spreading underground), forming a dense sod and mat-forming over time.
Sunlight & Water Needs
Full Sun preferred; requires at least 6-8 hours of direct sun; high water needs (1-1.5 inches per week); moderate to low drought tolerance (enters dormancy during heat/drought); prefers well-drained, fertile soil with pH 6.0-7.0.
Mowing & Maintenance
Mowing height: 2.0-3.5 inches; high frequency; fertilization: 2-4 lbs N per 1000 sq ft per year; requires regular dethatching and aeration; high maintenance level.
Special Characteristics
Excellent traffic and wear tolerance due to rhizomes; susceptible to Dollar Spot, Necrotic Ring Spot, and Summer Patch (evident in the tan patches in the photo); low shade tolerance; excellent winter hardiness.
Ecological Information
Introduced and naturalized in North America; provides forage for livestock and wildlife; stabilizes soil effectively; can be invasive in native prairie restorations; often blended with Perennial Ryegrass or Fine Fescue.