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 Fairways
Variety / Cultivar
Midnight (known for dark blue-green color and aggressive spreading rhizomes)
Hardiness Zones
Thrives in USDA Hardiness Zones 3 through 7. Excellent cold tolerance, surviving harsh winters under snow cover, but goes semi-dormant during periods of extreme summer heat.
About This Grass
Forms a lush, dense, medium-textured turf with an attractive rich green to dark blue-green color. Mown height typically ranges from 2 to 3.5 inches, while unmown plants can reach 18 to 24 inches with distinctive pyramidal panicle seed heads.
Blade Characteristics
Medium width (3 to 4 mm), flat to slightly folded shape with characteristic boat-shaped tips. Vernation is folded in the bud. Color ranges from medium to dark blue-green with prominent parallel veins and a distinct midrib.
Root System
Moderately deep fibrous root system combined with strong underground rhizomes. Forms a very dense sod that resists weed invasion and provides high wear recovery, though establishment from seed is notoriously slow.
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 growth, with moderate to high water needs. Has poor to moderate drought tolerance, entering summer dormancy during extended dry periods, and prefers well-drained fertile soils with a pH of 6.0 to 7.0.
Mowing & Maintenance
Ideal mowing height is 2.0 to 3.0 inches. Requires a medium-high maintenance level, frequent mowing during peak spring/fall growth, regular fertilization (3-4 lbs N per 1000 sq ft annually), and periodic aeration and dethatching.
Special Characteristics
Exhibits excellent traffic and wear tolerance due to aggressive rhizomatous recovery, good cold hardiness, and fine texture. Moderate shade tolerance compared to fine fescues, and susceptible to certain diseases like dollar spot and leaf spot under stress.
Ecological Information
Introduced to North America by European settlers. Provides standard lawn ecosystem services including soil stabilization, carbon sequestration, and stormwater runoff mitigation. Frequently blended with Perennial Ryegrass and Fine Fescues for northern lawn seed mixes.