Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, subfamily Pooideae, tribe Poeae
Grass Category
Lawn/Turf Grass
Variety / Cultivar
Common blend/mix (cultivars such as 'Midnight', 'Bewitched', or 'Baron' are typical in residential settings)
Hardiness Zones
Thrives in USDA Hardiness Zones 3 through 7. Excellent cold tolerance, but can struggle with extreme summer heat and humidity in southern zones unless irrigated.
About This Grass
Forms a dense, fine-to-medium textured turf with a rich medium-to-dark green color. When unmowed, it can reach heights of 18 to 24 inches, but when maintained as a lawn it is kept much lower. Features pyramid-shaped panicle seed heads at maturity.
Blade Characteristics
Blades are medium in width (2-4mm), flat to folded with prominent parallel veins and a distinctive boat-shaped tip. Vernation is folded in the bud. The ligule is short and membranous, and auricles are absent.
Root System
Fibrous and rhizomatous root system with moderate depth. Forms a very dense sod that provides excellent wear recovery, though it has a slower establishment rate from seed compared to ryegrass.
Growing Information
Origin Region
Native to Europe, northern Asia, and parts of the mountains of North America; widely cultivated and naturalized throughout the northern United States, Canada, and cool temperate regions globally.
Growth Habit
Rhizomatous, spreading extensively via underground stems to form a dense, uniform turf mat.
Sunlight & Water Needs
Thrives in full sun (minimum 6 hours of direct sunlight) with moderate to high water needs. Has fair-to-moderate drought tolerance, entering summer dormancy during extended dry periods, and prefers well-drained, fertile soils with a pH of 6.0-7.0.
Mowing & Maintenance
Ideal mowing height ranges from 2.0 to 3.5 inches. Requires regular mowing frequency, medium-to-high fertilization (3-4 lbs N per 1000 sq ft annually), occasional dethatching due to dense rhizome production, and overall medium-to-high maintenance.
Special Characteristics
High wear tolerance and excellent self-repairing capabilities due to rhizomes. Good cold tolerance and winter color retention in milder winter areas, though it goes dormant in extreme cold or drought. Susceptible to certain diseases like dollar spot and leaf spot under high stress.
Ecological Information
Introduced species in North America widely used for turf. Provides standard ecosystem services of a managed lawn including soil stabilization and runoff reduction, though residential turf has lower native biodiversity value compared to native prairies.