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 Grass
Variety / Cultivar
General species profile (common cultivars include 'Midnight', 'Baron', 'Compact')
Hardiness Zones
USDA Hardiness Zones 3 to 7; highly cold tolerant, goes dormant in freezing winters, and struggles under extreme, prolonged summer heat without adequate irrigation.
About This Grass
Forms a dense, medium-textured turf with a rich dark green to blue-green color. Mown height typically maintained at 1.5 to 2.5 inches, while unmowed mature height can reach 18 to 24 inches with open, pyramidal panicle seed heads.
Blade Characteristics
Medium width (2-4mm), folded in the bud (vernation), with distinctive boat-shaped tips and parallel veins. Membranous ligule, absence of prominent auricles, and a distinct whitish collar region.
Root System
Moderately deep fibrous root system combined with an extensive network of underground rhizomes. Tends to build thatch over time if unmanaged; establishes relatively slowly from seed but forms exceptionally tough, dense sod.
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 horizontal shoots to form a dense, uniform turf mat
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily) for optimal performance; moderate to high water needs; goes into summer dormancy during extended droughts but recovers well with irrigation.
Mowing & Maintenance
Ideal mowing height ranges from 2.0 to 3.5 inches. Requires a medium-to-high maintenance level including regular fertilization (3-4 lbs N per 1000 sq ft annually), periodic dethatching, and core aeration.
Special Characteristics
Excellent traffic and wear tolerance due to aggressive rhizomatous recovery, good cold hardiness, moderate disease susceptibility (e.g., dollar spot, summer patch), and poor shade tolerance compared to fescues.
Ecological Information
Introduced species in North America; provides effective soil stabilization and erosion control through its dense root and rhizome matrix, frequently blended with perennial ryegrass and tall fescue for residential and commercial turf.