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/tees)
Variety / Cultivar
Commonly found in many proprietary blends such as 'Midnight', 'America', or 'Baron'; appears to be a modern dark-green turf-type cultivar.
Hardiness Zones
USDA Zones 2-7; excellent cold tolerance but struggles in the heat of the Deep South (Zones 8-10). Becomes dormant and turns straw-colored in winter in very cold climates.
About This Grass
A dense, lush, cool-season grass with a prominent dark green to blue-green color. It maintains a soft texture and uniform appearance. When unmowed, it can reach 12-24 inches with open, pyramidal panicle seed heads. Under maintenance, it provides a thick, carpet-like turf.
Blade Characteristics
Fine to medium width (2-4mm). The most distinguishing feature is the 'boat-shaped' tip (curved upward like the prow of a boat). Blades are folded in the bud (folded vernation), smooth on both sides with a distinct midrib. Ligule is short and membranous; auricles are absent.
Root System
Relatively shallow fibrous root system compared to tall fescue, but develops extensive rhizomes. It has a moderate to high thatch-forming tendency and moderate establishment speed from seed (often 14-21 days to germinate).
Growing Information
Origin Region
Native to Europe, North Africa, and Asia; widely naturalized and the primary lawn grass across North America and temperate climates globally.
Growth Habit
Rhizomatous (spreading via underground stems). It forms a dense, sod-forming mat that is capable of self-repairing small patches.
Sunlight & Water Needs
Prefers Full Sun (6+ hours); has poor shade tolerance. High water needs to stay green during summer; will go dormant (turn brown) during severe drought to protect the crown but recovers once water returns. Prefers well-drained soil with pH 6.0 to 7.0.
Mowing & Maintenance
Ideal height 2.0 to 3.5 inches. High maintenance level; requires 2-4 lbs of Nitrogen per 1000 sq ft annually. Requires periodic dethatching and aeration due to rhizomatous growth and high density.
Special Characteristics
Excellent wear tolerance and recovery due to rhizomes. Susceptible to summer patch, necrotic ring spot, and powdery mildew in shade. High aesthetic value with deep color and soft feel.
Ecological Information
Introduced/Naturalized in North America. Provides soil stabilization and high water filtration. Often used in 'Northern Mixes' alongside Perennial Ryegrass and Fine Fescues to provide a balance of quick establishment, shade tolerance, and self-repairing ability.