Kentucky bluegrass (Poa pratensis)
SCIENTIFIC SYNONYMS: There are no scientific synonyms for
TAXONOMY: The currently accepted scientific name for Kentucky
bluegrass is Poa pratensis L.
Four subspecies have been recognized: 1) Poa pratensis ssp. agassi-
zensis (Boivin & D. Love) Taylor & McBryde; 2) Poa pratensis ssp.
alpigena (Fries) Hiitonen; 3) Poa pratensis ssp. angustifolia (L.)
Gaudin; 4) Poa pratensis ssp. pratensis.
Poa pratensis naturally hybridizes with several other species within
the genus, including Poa secunda, Poa arctica, Poa alpina, Poa ner-
vosa, Poa reflexa, and Poa palustris.
NATIVE STATUS: Native and introduced, United States and Canada.
Kentucky bluegrass is generally considered to be nonnative to North
America. Some botanists argue, however, that populations in remote
mountain meadows of the West may be native.
GENERAL BOTANICAL CHARACTERISTICS: Kentucky bluegrass,
is a perennial, cool-season, sod-forming grass native to Europe. Seedhead
stems are 18 to 24 inches tall, but can be 4 to 6 inches in height when used
for intensive grazing. The seedhead has an open shape like a pyramid and produces many small seeds. There are approximately 2,177,000 seeds per
pound. Leaves are 6 to 12 inches long and boat-shaped (keeled) at the tips.
Leaves are smooth, soft, and about 1/8 to 1/4 inch wide. The plant becomes
dormant during the heat of summer, but regains or maintains its green color
in fall. Growth starts early in the spring. Tiller buds develop into stems or rhizomes. New rhizomes also arise from nodes of older rhizomes. Most
rhizomes penetrate 2 to 4 inches into the soil, but some will go down more
than 5 inches.
REGENERATION PROCESSES: Kentucky bluegrass propogates
itself by reseeding and vegetative spread (rhizomes).
HABITAT TYPES: It has, however, become naturalized across North
America and often occurs as a herbaceous layer dominant. In the West,
Kentucky bluegrass frequently occurs as an understory dominant in aspen
(Populus tremuloides), ponderosa pine (Pinus ponderosa), sagebrush
(Artemisia spp.)/bunchgrass (Pseudoroegneria spicata, Festuca altaica,
F. idahoensis), bunchgrass, and riparian habitats. It is also a common
dominant of midwestern prairies.
Grazing-induced seral stages in which Kentucky bluegrass is the herba-
ceous layer dominant are widespread and common within ponderosa pine/
bunchgrass, sagebrush/bunchgrass, and bunchgrass habitat types Kentucky
bluegrass grows in meadows, fields, roadsides, open woods, and stream-
sides. It can grow in dry or moist soil. It is very competitive and will often
crowd out other plants.
SITE CHARACTERISTICS: Kentucky bluegrass is used throughout
the U.S. It is best adapted to well-drained, fertile, medium-textured soils
of limestone origin. It performs satisfactorily on poorly drained and heavy-textured soils. Favorable pH level for this grass is 6.0 to 7.5. Kentucky
bluegrass grows best in the humid areas. Optimum temperatures for for-
age production are between 60 F and 90°F. Although the grass is essent-
ially dormant during dry or excessively hot weather, it survives severe
droughts. It prefers sunlight but will do well in light shade with ample
moisture and nutrients.
SEASONAL DEVELOPMENT: Kentucky bluegrass is one of the first
grasses to resume growth in late winter or early spring. It grows rapidly,
and in many states it flowers in May. Most flowering occurrs in late May
and early June (some flowering can continue into August). By midsummer
plants become nearly dormant. With cool temperatures and precipitation,
growth resumes in the fall and continues until daytime temperatures
GENERAL DISTRIBUTION: Kentucky bluegrass is now found in all
states and provinces of the United States and Canada. It is adapted for
growth in cool, humid climates, and is most prevalent in the northern half
of the United States and the southern half of Canada. It is not common in
the Gulf States nor in desert regions of the Southwest.
SKY MEADOWS DISTRIBUTION: To be determined.
IMPORTANCE AND USES: This plant is highly palatable to elk and is
one of the better grasses for deer. The tender plants are grazed immediate-
ly after growth begins and the leaves remain succulent and green as long
as soil moisture is present. Seeds are eaten by several kinds of songbirds
and rodents. Leaves are eaten by rabbits and turkey.
This plant provides a dense green sod especially adapted for parks and
home lawns. It can, however, become weedy or invasive in some regions
or habitats and may displace desirable vegetation if not properly managed.
Kentucky bluegrass is an excellent erosion control plant because of its
dense, vigorous turf forming habit. It can be used as a mix with legumes
or other grasses for erosion control in conservation cover, waterways, field borders, heavy use areas and critical areas such as steep banks and pond
edges. It is also used alone or in seed mixtures as permanent cover for tree plantings and orchards.
The species is highly palatable to horses, cattle, and sheep. It produces re-
latively low yields compared to other pasture grasses, but can be very pro-
ductive in the Northeast on closely grazed intensive rotational grazing
Kentucky bluegrass turf is excellent for ball fields and other heavy use
areas such as camp grounds, golf fairways, and picnic areas.
Crooked Run Valley