Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, subfamily Pooideae, tribe Poeae
Grass Category
Lawn/Turf Grass and Pasture Grass
Variety / Cultivar
Common or 'Naturalized' type (based on tall, open seed heads and clumping/patchy growth in unmaintained state)
Hardiness Zones
USDA Zones 2-7; excellent cold tolerance, poor heat tolerance (enters dormancy/browns during hot, dry summers).
About This Grass
Medium-green to dark-green perennial grass. When unmown, it reaches 12-24 inches. It features a characteristic open, pyramidal panicle seed head with small spikelets. The blades are upright and form a dense sod over time.
Blade Characteristics
Fine to medium width (2-4mm), folded vernation in the bud, distinctive boat-shaped tips. Deep green color with a prominent central vein (keel). Ligule is short, membranous, and truncated; auricles are absent.
Root System
Moderately deep fibrous root system with extensive horizontal rhizomes. High thatch tendency; excellent sod-forming ability and recovery from wear due to rhizomes.
Growing Information
Origin Region
Native to Europe, Asia, and North Africa; widely naturalized across North America
Growth Habit
Rhizomatous (underground spreading) but appears in dense tufts when left to grow tall; mat-forming when maintained
Sunlight & Water Needs
Prefers Full Sun (6+ hours) but tolerates light shade; high water requirement during summer heat. Prefers well-drained, slightly acidic to neutral soils (pH 6.0-7.0).
Mowing & Maintenance
Ideal height 2.5-3.5 inches; frequent mowing needed in spring/fall. High nitrogen requirement (3-4 lbs N per 1000 sq ft/year). Requires periodic dethatching and aeration.
Special Characteristics
Excellent traffic tolerance and recovery; high aesthetic appeal. Susceptible to Leaf Spot, Dollar Spot, and Necrotic Ring Spot. 'Self-repairing' due to rhizomes.
Ecological Information
Introduced species in North America. Provides forage for livestock and nesting cover for small birds. Used widely for soil stabilization. Often mixed with Perennial Ryegrass or Fine Fescue.