Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, subfamily Pooideae, tribe Poeae
Grass Category
Lawn/Turf Grass, Sports Turf
Variety / Cultivar
Midnight (known for dark blue-green color and high density)
Hardiness Zones
USDA Hardiness Zones 3-7, with good cold tolerance down to extreme sub-zero temperatures. Heat tolerance is moderate, often struggling in deep southern climates unless heavily irrigated. Enters winter dormancy in colder regions.
About This Grass
Forms a dense, high-quality turf with a rich medium-to-dark green or blue-green color. Reaches 18-24 inches if left unmowed but is typically maintained at 1.5 to 2.5 inches. Fine to medium texture with a neat, upright growth habit and open panicle seed heads at maturity.
Blade Characteristics
Medium width (2-4mm), flat to folded shape with distinctive boat-shaped tips and prominent parallel veins. Vernation is folded in the bud. Features a short, membranous ligule and lacks auricles, with a broad continuous collar.
Root System
Moderately deep fibrous root system with extensive underground rhizomes. Tends to build moderate thatch over time. Slow to germinate and establish from seed, but forms an extremely tough, wear-resistant sod once mature.
Growing Information
Origin Region
Europe and Northern Asia; widely naturalized and cultivated across North America, performing best in northern and transition zones
Growth Habit
Aggressively rhizomatous, spreading via underground stems to form a dense, uniform turf mat
Sunlight & Water Needs
Performs best in full sun (minimum 6-8 hours daily), with moderate to high water needs to maintain summer greenness. Fair to moderate drought tolerance, entering summer dormancy during severe dry spells and recovering when moisture returns. Prefers well-drained, fertile soils with a pH of 6.0 to 7.0.
Mowing & Maintenance
Ideal mowing height ranges from 2.0 to 3.0 inches. Requires regular mowing during peak spring and fall growth periods. Medium to high maintenance level, needing 3-4 lbs of nitrogen per 1000 sq ft annually, regular irrigation, and periodic dethatching and aeration.
Special Characteristics
Excellent wear tolerance and recovery due to aggressive rhizomes. Good cold hardiness and winter color retention in milder winter zones. Moderate disease susceptibility (e.g., dollar spot, leaf spot, summer patch). Poor shade tolerance compared to fine fescues.
Ecological Information
Introduced species in North America widely used for erosion control, residential lawns, and athletic fields. Provides standard turf ecosystem services including soil stabilization, carbon sequestration, and stormwater runoff reduction. Frequently blended with perennial ryegrass and fine fescues.