Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass; not typically a transition zone grass on its own but heavily used in northern transition zones.
Grass Family
Poaceae, subfamily Pooideae, tribe Poeae
Grass Category
Lawn/Turf Grass, Sports Turf, Golf Course Grass (Fairways/Tees)
Variety / Cultivar
Standard turf-type cultivar (e.g., 'Midnight' or similar dark green, dense-forming varieties)
Hardiness Zones
Thrives in USDA Hardiness Zones 3 to 7. Excellent cold tolerance, surviving harsh northern winters underground via rhizomes. Goes semi-dormant or dormant in extreme summer heat.
About This Grass
Forms a dense, fine-to-medium textured turf with an attractive dark green to blue-green color. Reaches up to 18-24 inches if unmowed, but maintained as turf at 1.5-2.5 inches. Features folded vernation in the bud shoot and boat-shaped leaf tips.
Blade Characteristics
Fine to medium width (2-4 mm), flat or folded with distinct parallel veins and characteristic boat-shaped (prow-shaped) tips. Color is rich blue-green. Vernation is folded in the bud. Ligule is short and membranous, auricles are absent.
Root System
Moderately deep fibrous root system combined with strong spreading rhizomes. Forms a very dense sod that recovers well from wear via rhizome spread, though initial establishment from seed is notoriously slow.
Growing Information
Origin Region
Native to Europe, northern Asia, and parts of the mountainous regions of North America. Widely cultivated throughout the northern United States, Canada, and cool temperate regions worldwide.
Growth Habit
Rhizomatous, spreading underground via extensive aggressive lateral stems (rhizomes) to form a dense, uniform turf mat.
Sunlight & Water Needs
Requires full sun (minimum 6-8 hours daily), though some modern cultivars have moderate shade tolerance. High water requirements to maintain green color during summer; goes into summer dormancy (turning brown) during drought but recovers when moisture returns.
Mowing & Maintenance
Ideal mowing height is 2.0 to 3.0 inches. Mowing frequency is high during peak spring and fall growth periods. Requires moderate to high fertility (3-4 lbs N per 1000 sq ft annually). High maintenance level, prone to thatch buildup.
Special Characteristics
Exceptional traffic and wear tolerance due to aggressive rhizomatous recovery. Good cold hardiness and winter color retention compared to warm-season grasses. Susceptible to certain diseases like dollar spot, leaf spot, and summer patch.
Ecological Information
Widely naturalized in North America. Excellent for soil erosion control, stabilization, and stormwater filtration due to dense root and rhizome matrix. Frequently blended with Perennial Ryegrass and Fine Fescue.