Kentucky Bluegrass

(Poa pratensis L.)

Interesting Information About Plant:  

     Kentucky Bluegrass is a common lawn and prairie grass and because it grows early in the season, while other plants are still dormant, it can spread rather rapidly.  The plant will spread by rhizomes, which are roots that grow sideways underground.  This plant is so competitive that it is known to push other grass species out, taking control of the area in which it was planted.  The shallow root system of the plant makes it susceptible to high soil temperature and low soil moisture.  The plant needs plenty of sunshine and moisture to grow, if there is limited moisture, as in summer, the plant will resort to a dormant stage until there is sufficient moisture present.  The plant grows best in soil that contains loam, clay loam, and sand.  There are some fungi that attack Kentucky bluegrass, the most common being powdery mildew.  There is no medical value associated with this plant; however horses and other farm animals seem to like to eat this grass.  Kentucky bluegrass is tall enough that it provides cover for small animals, reptiles, and amphibians.  This plant is also used by ground nesting birds, such as the wild turkey, to build nests with.  Certain birds and insects like to eat this plant as well.  This plant acquired its name because as one looks at the grass in the sun, it appears to have a bluish tint to it. 

Common Name(s): Kentucky bluegrass; June Grass; Smooth Meadow Grass

Scientific Name: Poa pratensis L.

Family Name (Scientific and Common): Poaceae  (Grass Family)

Continent of Origin: Some forms native to US, others from Europe

Plant Growth Habit: Ground Cover

Height at Maturity: Between 1- 3 Feet

Life Span: Perennial

Seasonal Habit: Herbaceous That Stays Green Through Winter 

Growth Habitat: Full Sun 

Manner of Culture: Native Species commonly used in Turf Landscapes

Thorns on Younger Stem: No

Cross Section of Younger Stem: Roundish  

Stem (or Trunk) Diameter: Less Than The Diameter of a Pencil  

Produces Brownish Bark: No

Bark Peeling in Many Areas: No

Characteristics of Mature (Brownish) Bark: No Mature Bark (all green)

Type of Leaf: Flat, Thin Leaf  

Length of Leaf (or Leaflet): Between the Length of a Credit Card and a Writing-Pen (depends on mowing)    

Leaf Complexity: Simple 

Edge of Leaf: Smooth 

Leaf Arrangement: Alternate

Leaf has Petiole: Yes  (grasslike)

Patterns of Main-Veins on Leaf (or Leaflet): Parallel 

Leaf Hairiness: No Hairs

Color of Foliage in Summer: Green 

Change in Color of Foliage in October: No

Flowering Season: Summer

Flowers: In Loose Group  (Panicle)

Type of Flower: Like a Grass Flower 

Color of Flower: Greenish

Shape of Individual Flower: Bilaterally Symmetrical (Grass like)

Size of Individual Flower: Smaller than a Quarter  

Sexuality: Hermaphroditic

Size of Fruit: Smaller Than a Quarter

Fruit Fleshiness: Dry at Maturity

Shape of Fruit: Spherical

Color of Fruit at Maturity: Brown, Dry

Fruit Desirable to Birds or Squirrels:  Yes 

Louisville Plants That Are Most Easily Confused With This One: Annual Bluegrass, other turf species

Unique Morphological Features of Plant: Leaf tip is fused to form a boat-like structure; Leaves have a prominent, translucent ligule around stem; has rhizomes (underground horizontal stems) that help it spread

Poisonous:  None of Plant

Pestiness (weedy, hard to control): Yes  

Page prepared by:

Daniel Dierfeld

November 2004