Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, subfamily Pooideae
Grass Category
Lawn/Turf Grass, Sports Turf, Golf Course Grass
Variety / Cultivar
'Midnight', known for dark blue-green color and excellent density
Hardiness Zones
Thrives in USDA Hardiness Zones 3 through 7, exhibiting excellent cold tolerance and winter dormancy, but struggles with extreme summer heat in deep southern climates.
About This Grass
Forms a very dense, fine to medium-textured turf with an attractive rich green to dark blue-green color. Mown height typically ranges from 1.5 to 2.5 inches, while unmowed growth can reach 18 to 24 inches with open, pyramidal panicle seed heads.
Blade Characteristics
Blades are medium-width (2-4mm), flat to folded with prominent parallel veins creating a railroad-track appearance. The tips are distinctly boat-shaped (keeled). Vernation is folded in the bud with a short, membranous ligule and absent auricles.
Root System
Moderate to deep fibrous root system combined with strong underground rhizomes. Forms a dense, tough sod that resists wear, though initial establishment from seed is slow.
Growing Information
Origin Region
Europe and Northern Asia; widely cultivated across North America and temperate regions globally
Growth Habit
Rhizomatous, spreading underground via vigorous rootstocks to form a dense sod
Sunlight & Water Needs
Requires full sun (minimum 6 hours of direct sunlight) and moderate to high moisture. Moderate drought tolerance, entering dormancy during prolonged dry spells; prefers well-drained soils with a pH between 6.0 and 7.0.
Mowing & Maintenance
Maintain mowing height between 2.0 and 3.0 inches. Requires regular fertilization (3-4 lbs N per 1000 sq ft annually), occasional dethatching due to dense sod formation, and regular watering. Considered a high-maintenance turf grass.
Special Characteristics
Exceptional wear tolerance and natural ability to self-repair via rhizomes. Good cold tolerance and winter color retention compared to warm-season grasses. Susceptible to certain diseases like dollar spot and leaf spot under high humidity.
Ecological Information
Introduced species in North America. Provides good soil stabilization and erosion control due to dense root and rhizome matrix. Commonly blended with perennial ryegrass and fine fescues for home lawns and sports fields.