Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, subfamily Pooideae
Grass Category
Lawn/Turf Grass, Sports Turf
Variety / Cultivar
Midnight (known for dark blue-green color and dense growth)
Hardiness Zones
USDA Hardiness Zones 3 to 7; excellent cold tolerance; struggles in extreme southern heat unless irrigated; performs exceptionally well in northern transition zones and cool-temperate regions.
About This Grass
Forms a dense, high-quality turf with medium-fine texture and rich blue-green color; maintains color well in cool weather but can go dormant in extreme summer heat or drought; height ranges from 1.5 to 2.5 inches when maintained.
Blade Characteristics
Medium-fine width (2-4mm); flat to folded shape with distinctive boat-shaped tips; blue-green to dark green color; folded vernation in the bud; prominent parallel veins with a light-colored midrib; short membranous ligule and absent auricles.
Root System
Moderately deep fibrous root system combined with extensive underground rhizomes; forms a very dense sod; medium-slow establishment rate; high thatch-forming tendency under high maintenance.
Growing Information
Origin Region
Europe and Northern Asia; widely naturalized and cultivated across North America and temperate regions worldwide
Growth Habit
Rhizomatous, spreading underground via aggressive rhizomes to form a dense, uniform sod
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily); moderate to high water needs; moderate drought tolerance by entering summer dormancy; prefers well-drained fertile soils with a pH of 6.0 to 7.0.
Mowing & Maintenance
Mowing height between 2.0 to 3.0 inches; regular weekly mowing during peak growing seasons; high fertilization needs (3-4 lbs N per 1000 sq ft annually); requires periodic dethatching and core aeration; high maintenance level.
Special Characteristics
Good wear tolerance and excellent self-repairing ability due to aggressive rhizomes; moderate disease susceptibility (susceptible to dollar spot, leaf spot, and summer patch); good shade tolerance compared to some warm-season grasses but generally prefers full sun.
Ecological Information
Introduced species in North America; provides standard wildlife and lawn ecosystem functions; excellent for erosion control on slopes due to dense sod formation; frequently blended with perennial ryegrass and fine fescues for turf durability.