Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, Subfamily Pooideae, Tribe Poeae
Grass Category
Lawn/Turf Grass, Sports Turf, Golf Course Fairways
Variety / Cultivar
Common/Mixed Cultivar (e.g., Midnight, Blue Note, or Mazama common in turf mixes)
Hardiness Zones
USDA Hardiness Zones 2-7; excellent cold tolerance but goes dormant (brown) during extreme heat or drought; well-suited for northern climates.
About This Grass
A dark-green, cool-season turfgrass known for its smooth texture and high density. It reaches 12-24 inches if unmowed, producing panicle-shaped seed heads. In the image, it exhibits patches of dormancy or stress-related browning common during summer heat or disease stress.
Blade Characteristics
Fine to medium width (2-4mm); flat or slightly V-shaped; distinctive boat-shaped (keeled) tip. Color ranges from deep emerald to blue-green. Vernation is folded in the bud; ligule is short and membranous; auricles are absent.
Root System
Moderately shallow fibrous root system with extensive horizontal rhizomes. Forms a thick, durable sod but possesses moderate thatch-forming tendencies. Rapid establishment from sod, slower from seed.
Growing Information
Origin Region
Native to Europe, North Asia, and Morocco; widely naturalized in North America and cool temperate regions
Growth Habit
Rhizomatous; spreads via underground stems to form a dense, uniform sod with high self-repair capability
Sunlight & Water Needs
Full sun preferred (6+ hours); poor shade tolerance. Requires moderate to high watering; high humidity can increase disease pressure. Prefers well-drained, fertile soil with pH 6.0-7.5.
Mowing & Maintenance
Ideal height 2.0-3.5 inches. High maintenance; requires 2-4 lbs Nitrogen per 1000 sq ft annually. Requires regular dethatching and aeration to manage biomass.
Special Characteristics
Excellent wear tolerance and recovery due to rhizomes; susceptible to Dollar Spot, Summer Patch (visible in image patches), and Necrotic Ring Spot. Poor salt tolerance.
Ecological Information
Introduced/Naturalized in North America; provides soil stabilization via dense sod; offers forage for small mammals and nesting cover when unmowed; often blended with Perennial Ryegrass or Fine Fescue for genetic diversity.