Kentucky Bluegrass
Poa pratensis · Cool-season, Perennial, C3 grass
Grass Family
Poaceae, Subfamily Pooideae
Grass Category
Lawn/Turf Grass
Variety / Cultivar
Common or 'Midnight' type (unspecified variety based on image)
Hardiness Zones
USDA Hardiness Zones 2-7; excellent cold tolerance but struggles in the heat of the humid South (Zones 8 and above).
About This Grass
A medium-textured turfgrass that produces a lush, dark green lawn under ideal conditions. It enters summer dormancy (turning brown/tan as seen in the image) during periods of high heat and drought to protect the crown.
Blade Characteristics
Blade width is medium (2-4mm). The most identifying feature is the boat-shaped (V-shaped) leaf tip and two distinct translucent lines (mid-rib) on either side of the center. Vernation is folded in the bud; ligules are short and membranous; auricles are absent.
Root System
Moderately shallow fibrous roots with extensive horizontal rhizomes. It is known for high thatch-forming tendencies and excellent sod-knitting ability, allowing it to recover from wear by filling in bare spots.
Growing Information
Origin Region
Europe, Northern Asia, and North Africa; now naturalized throughout temperate North America
Growth Habit
Rhizomatous (spreading via underground stems), forming a dense, sod-forming mat
Sunlight & Water Needs
Prefers full sun (minimum 6 hours) but has moderate shade tolerance. High water requirements; requires approximately 1-1.5 inches of water per week to stay green. High drought dormancy, but low drought resistance compared to fescues.
Mowing & Maintenance
Ideal mowing height is 2.5 to 3.5 inches. High maintenance level; requires regular fertilization (3-5 lbs N per 1000 sq ft annually) and periodic dethatching/aeration due to rhizomatous growth.
Special Characteristics
Excellent traffic tolerance and recovery due to rhizomes. Susceptible to Leaf Spot, Dollar Spot, and Summer Patch. It provides the quintessential 'golf course' look for home lawns in northern climates.
Ecological Information
Introduced and naturalized in North America. Provides habitat for small insects and soil stabilization for erosion control. Often blended with Perennial Ryegrass or Fine Fescue to improve disease resistance and shade tolerance.