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 (Fairways and Tees)
Variety / Cultivar
Common architectural types include "Midnight" or "Baron"; the image shows a high-density, dark green turf-type variety common in residential lawns.
Hardiness Zones
USDA Zones 2-7; excellent cold tolerance (to -30F). Poor heat tolerance; often goes dormant in summer without irrigation.
About This Grass
A dark green, high-density perennial grass with a medium to fine texture. It produces a luxurious, carpet-like appearance and enters dormancy during extreme heat or drought. Seed heads are open panicles, though rarely seen in maintained lawns.
Blade Characteristics
Width: 2-4mm (medium); Shape: Flat or slightly V-shaped; Tip: Distinctive boat-shaped (keeled) tip; Color: Rich dark green to blue-green; Vernation: Folded in the bud; Ligule: Short, membranous, and truncated; Auricles: Absent; Collar: Divided, smooth.
Root System
Moderately shallow fibrous root system with extensive horizontal rhizomes. High thatch-forming tendency; slow to moderate establishment from seed but forms a very durable sod once established.
Growing Information
Origin Region
Native to Europe, North Asia, and the mountains of Algeria and Morocco; widely naturalized in North America and cool temperate climates globally.
Growth Habit
Rhizomatous (spreading underground). Forms a dense, thick sod that is self-repairing through lateral underground stems.
Sunlight & Water Needs
Full Sun (minimum 6 hours) preferred; moderate shade tolerance. High watering needs; requires 1-1.5 inches of water per week. Well-drained soil with a pH of 6.0 to 7.0 is ideal.
Mowing & Maintenance
Ideal height: 2.0-3.5 inches. Mowing frequency: Weekly during active growth. Fertilization: 3-5 lbs N per 1000 sq ft per year. High maintenance; requires regular aeration and dethatching.
Special Characteristics
Excellent wear tolerance and recovery due to rhizomes. Good disease resistance in modern cultivars, though susceptible to leaf spot and necrotic ring spot. Highly valued for home lawns and sports fields for its soft feel and uniform appearance.
Ecological Information
Introduced species in North America but naturalized; helps stabilize soil and prevent erosion. Provides cover for small insects and invertebrates. Commonly blended with Perennial Ryegrass or Fine Fescues to improve genetic diversity and shade tolerance.