Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, Subfamily Pooideae, Tribe Poeae
Grass Category
Lawn/Turf Grass
Variety / Cultivar
Likely a blend of Kentucky Bluegrass cultivars (e.g., Midnight, Baron, or similar high-density turf types) common in residential lawns.
Hardiness Zones
USDA Hardiness Zones 2 through 7. Excellent cold tolerance; enters dormancy in temperatures above 85°F or below freezing.
About This Grass
A dense, high-quality turf grass with a dark-green to blue-green color. It exhibits a uniform texture and grows 12-24 inches when left unmowed, though typically maintained at 2-3 inches. It features a panicle-shaped seed head and goes dormant during extreme summer heat or winter cold.
Blade Characteristics
Medium blade width (2-4mm), V-shaped or flat cross-section, with a distinctive boat-shaped (keeled) tip. The vernation is folded in the bud; the ligule is very short and membranous; auricles are absent. The upper leaf surface often shows two clear 'tracks' or lines on either side of the mid-vein.
Root System
Moderately deep fibrous root system supplemented by strong rhizomes. It has a high thatch-forming tendency but offers excellent recovery from wear due to its spreading habit. Establishment is slow compared to ryegrass.
Growing Information
Origin Region
Native to Europe, Asia, and North Africa; naturalized throughout North America and thrives in temperate, humid regions.
Growth Habit
Rhizomatous (spreading underground via rhizomes), forming a dense, tight-knit sod mat.
Sunlight & Water Needs
Full sun preferred (requires at least 6-8 hours); moderate shade tolerance. High watering needs (1 inch per week) to maintain green color during summer; has good drought dormancy but poor drought avoidance.
Mowing & Maintenance
Ideal height 2.0 to 3.5 inches. High maintenance level requiring 2-4 lbs of Nitrogen per 1,000 sq ft annually. Regular aeration and occasional dethatching are necessary due to rhizome density.
Special Characteristics
Excellent wear tolerance and recovery; good disease resistance in modern cultivars (though susceptible to leaf spot and dollar spot). Highly valued for its soft feel, dark color, and ability to self-repair bare spots.
Ecological Information
Introduced status in North America; provides cover for small insects and invertebrates; excellent soil stabilizer for erosion control; often blended with Perennial Ryegrass or Fine Fescue for improved resilience.