Kentucky Bluegrass (Pratensis)

The Kentucky Bluegrass (Pratensis) is generally described as a perennial graminoid. This is not native to the U.S. (United States) and has its most active growth period in the spring and summer and fall . The greatest bloom is usually observed in the mid spring, with fruit and seed production starting in the spring and continuing until summer. Leaves are not retained year to year. The Kentucky Bluegrass (Pratensis) has a long life span relative to most other plant species and a moderate growth rate. At maturity, the typical Kentucky Bluegrass (Pratensis) will reach up to 1.5 foot high, with a maximum height at 20 years of 0 inches.

The Kentucky Bluegrass (Pratensis) is easily found in nurseries, garden stores and other plant dealers and distributors. It can be propagated by seed. It has a slow ability to spread through seed production and the seedlings have low vigor. Note that cold stratification is not required for seed germination and the plant cannot survive exposure to temperatures below -38°F. has low tolerance to drought and restricted water conditions.

Uses of : Landscaping, Medicinal, Culinary, etc.

Landscape: Kentucky bluegrass is a popular sod-forming grass that is used on golf courses, ski slopes, and campsites.

Livestock: Kentucky bluegrass is an important forage species for sheep and cattle. In the west, it is very abundant and frequently used as a forage crop. In the east, it is planted as a pasture grass. It is not usually used for hay, but it has been found as an invader of hay mixes.

Rehabilitation: Kentucky bluegrass is included in seed mixes that are used to revegetate roadbanks. It is a slow-growing plant, establishes in 2 to 3 years and forms a dense sod. It is not as good at stabilizing soil as its native counterparts.

Wildlife: Elk, mule deer, and bighorn sheep eat Kentucky bluegrass. It is an important winter forage grass for these animals in the west. Cottontail rabbit, wild turkey, and prairie chickens consume the leaves and seeds of Kentucky bluegrass. In the mountain meadows of Oregon, the northern pocket gopher, mice, and Columbian ground squirrel feed off of the dominating Kentucky bluegrass. Therefore this is an important habitat for foraging raptors. Kentucky bluegrass also provides cover for small mammals and nongame birds.

General Characteristics

General: Grass Family (Poaceae). Kentucky bluegrass is a cool-season perennial sod-forming grass. The roots are shallow, often within the upper 8 cm of the soil surface. Stems are 30 to 90 cm tall. Leaves are attached to the base of the stem, folded and sometimes hairy at the point of attachment, have flat blades, are 2 to 5 mm wide and 10 to 40 cm long. The inflorescence is an open panicle consisting of two to six flowers. The lemmas have a tuft of cobwebby hairs. Flowering starts in May and fruit is mature by mid-June.

Kentucky bluegrass is distinguished from Canada bluegrass (Poa compressus) by its darker green foliage, longer leaves, and pubescence at the bases of the leaves.

Required Growing Conditions

Kentucky bluegrass is native to portions of North America, including areas within the United States. Exact delineation of native status has not been determined, but data seems to indicate that it is native in parts of the southeast, northeast, and upper Midwest regions and introduced or naturalized elsewhere. It occurs throughout the United States although it is most prevalent in the northern half. It is not common in the Gulf States or in the desert regions of the southwest. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site (http://plants.usda.gov).

Habitat: Kentucky bluegrass is promoted on sites that have cool and humid climates. It is found in uplands and lowlands of the tallgrass prairie and in the lowlands of mixed-grass prairies where adequate precipitation falls. In the west, it is found on northern exposures at mid to high elevations. In the southwest and California, it is found in cool mountainous regions.

It frequently occurs as an understory dominant in aspen habitats throughout the Intermountain Region, ponderosa pine, sagebrush/bunchgrass, and bunchgrass habitats throughout the U.S., and riparian habitats in the Mountain West. It is also a common dominant of Midwestern prairies.

Adaptation Kentucky bluegrass is found most abundantly on sites that are cool and humid. It has become naturalized across North America and often occurs as a dominant species in the herbaceous layer.

Kentucky bluegrass grows best on well-drained loams or clay loams rich in humus and on soils with limestone parent material. It needs large amounts of nitrogen during active growth stages. The optimal soil pH is between 5.8 and 8.2.

In the Blue Mountains of eastern Oregon and southeastern Washington, Kentucky bluegrass dominance is an indicator of dry to moist meadow conditions and of soils that are dark brown to black and clayey.

Kentucky bluegrass plants that have shorter leaves are more likely to produce tillers. Plants that occur in full sun have shorter leaves while those in shade have leaves longer than the stems. Therefore plants that are in full sun will produce more tillers and spread more quickly than those in the shade.

Kentucky bluegrass is intolerant of drought, excessive flooding, high water tables, and poorly drained soils.

Cultivation and Care

For lawn establishment, plant 2 to 3 pounds of seed per 1,000 square feet. Seeding rates are reduced when seed is drilled into the top 1 inch of soil. Kentucky bluegrass can be seeded year-round, but the best results are obtained in the spring and fall. Seeds require light and frequent watering (2 to 3 times per day for the first 2 weeks) for germination to occur. After seedling emergence, watering frequency can be reduced.

Status

Kentucky bluegrass is listed as an invasive weed in the Great Plains States and Wisconsin. Weediness This plant may become weedy or invasive in some regions or habitats and may displace desirable vegetation if not properly managed. Please consult with your local NRCS Field Office, Cooperative Extension Service office, or state natural resource or agriculture department regarding its status and use.

General Upkeep and Control

The active growth stage of Kentucky bluegrass begins in late winter/early spring. By midsummer it is nearly dominant on its sites. Cool temperatures in fall promote growth when other species are dying back. It spreads by rhizomes, produces abundant seed, and can become established on disturbed sites faster than other plant species. It is an aggressive competitor with native species.

Total replacement of Kentucky bluegrass by natives is labor-intensive and impractical. It is best to manage for warm season native grasses rather than against Kentucky bluegrass. In grasslands, atrazine and glyphosphate are effective herbicides for decreasing Kentucky bluegrass abundance when applied prior to seeding warm-season native grasses like big bluestem. Also, irregular spring and fall burns can help to control or maintain co-dominance of Kentucky bluegrass (as opposed to complete dominance).

Kentucky bluegrass pastures are best managed under a grazing system other than season-long use. At the end of the growing season, it becomes less palatable and protein and fiber contents decline. Pests and Potential Problems White grubs, billbugs and sod webworms can destroy plantings of bluegrass. Insect populations should be monitored so that timely insecticide applications can be made. Pest management in this manner is much more cost effective than routine insecticide applications or replanting large areas.

Kentucky bluegrass is sometimes vulnerable to fungal infections including Fusarium, Helminthosporium, leaf spot, rust and powdery mildew. Mixing bluegrass seed with ryegrass will prevent Fusarium blight.

Seeds and Plant Production Seeds are sown in springtime in a cold frame containing moist compost. Seedlings are thinned to individual pots and moved into a greenhouse where they will remain for the first winter. After the last spring frost, plant the seedlings into their permanent positions. Plant divisions can be directly planted into their permanent positions in late spring or early summer.

Plant Basics
Category
Growth Rate Moderate
General Type Graminoid
Growth Period Spring, Summer, Fall
Growth Duration Perennial
Lifespan Long
Plant Nativity Native and Introduced to U.S.
Commercial Availability Routinely Available
Physical Characteristics
Bloom Period Mid Spring
Displays Fall Colors No
Shape/Growth Form Rhizomatous
Drought Tolerance Low
Shade Tolerance Intolerant
Height When Mature 1.5
Vegetative Spread Rapid
Flower Color Yellow
Flower Conspicuousness No
Fruit/Seed Abundance High
Fruit/Seed Seasonality Spring Summer
Seed Spread Rate Slow
Gardening Characteristics
Propagations (Ways to Grow) Seed
Moisture Requirements High
Cold Stratification Required No
Minimum Temperature -38
Soil Depth for Roots 10
Toxic to Nearby Plants No
Toxic to Livestock No
After-Harvest Regrowth Rate Moderate
After-Harvest Resprout Ability No
Responds to Coppicing No
Growth Requirements
pH Range 5–8.4 pH
Precipitation Range 24–24 inches/yr
Planting Density 0–0 indiv./acre
Soil Textures Fine, Medium
Soil Depth for Roots 10
Minimum Frost-Free Days 90 day(s)
Salinity Tolerance Medium
CaCO3 Tolerance High
Sustainability & Use
Leaf Retention No
Palatability High
Fire Resistant No
Causes Livestock Bloating None

Source: USDA, NRCS, PLANTS Database, plants.usda.gov.
National Plant Data Center, Baton Rouge, LA 70874-4490 USA