4.15.2010

Kentucky Bluegrass Botanical Classification

Poa pratensis L.

Kingdom Plantae – Plants
Subkingdom Tracheobionta – Vascular plants
Superdivision Spermatophyta – Seed plants
Division Magnoliophyta – Flowering plants
Class Liliopsida – Monocotyledons
Subclass Commelinidae
Order Cyperales
Family Poaceae – Grass family
Genus Poa L. – bluegrass P
Species Poa pratensis L. – Kentucky bluegrass

http://plants.usda.gov/java/profile?symbol=POPR



Poa pratensis

Origins of Kentucky Bluegrass

Kentucky bluegrass is native to practically all of Europe, northern Asia and the mountains of Algeria and Morocco. Although the species is spread over all of the cool, humid parts of the U.S., it is not native to North America. Apparently the early colonists brought seed of Kentucky bluegrass to this country in mixtures with other grasses.

In the southern U.S., Kentucky bluegrass is limited to the transition zone from North Carolina, through much of Tennessee, northern Arkansas to the panhandle of Texas and Oklahoma. In the western states, Kentucky bluegrass is grown with irrigation.

http://aggie-horticulture.tamu.edu/plantanswers/turf/publications/bluegrass.html

Botanical Description


Kentucky Bluegrass is perennial with a widely creeping rootstock. This produces runners and leafy shoots. The runners are underground stems, carrying colourless scales instead of green leaves. They creep under the surface of the ground, rooting from the joints and finally producing upright, leafy stems from their ends. The leafy shoots are upright from the beginning and arise in bunches from the very base of the stems. They are round and have at first only leaves but develop later into flower-bearing stems. The stems are from one-half to three feet high, perfectly smooth. The stem leaves are comparatively short, only one or two inches long, and their apex is contracted somewhat after the fashion of the end of a canoe. The leaves of the basal shoots are longer and generally narrower than the stem leaves. Although showing considerable variation in colour, shape and size, the leaves have always this characteristic in common, that the ligule is very short and blunt. The flowers are in a panicle, pyramidal in shape during blossoming time and afterwards more or less contracted. Each branch of the panicle carries several spikelets. These are generally bluish - green-hence the name Blue Grass - but sometimes they have a purplish or violet shade. A spikelet has as a rule four or five flowers, each of which is enclosed within two glumes of equal size. Although the arrangement of stamens and pistils indicates that cross-fertilization would be easy, no doubt much self-fertilization takes place.

http://chestofbooks.com/flora-plants/weeds/Fodder-Pasture-Plants/Kentucky-Blue-Grass-Poa-Pratensis-L.html

Moderate to high quality depending on cultivar, management, and environment; medium texture; green to dark green with good density.

http://www.purdue.edu/envirosoft/lawn/src/grass/midwest.htm

Environmental Limitations and Tolerances


Kentucky Bluegrass is a Cool Season Grass.

Prefers well-drained, moist, neutral to slightly acid, fertile soils; full sun to light shade; good low-temperature tolerance; poor to fair drought tolerance, depending on management and cultivar.

http://www.purdue.edu/envirosoft/lawn/src/grass/midwest.htm

Root growth is greatest in fall and spring and slows dramatically in summer. Root growth of Kentucky bluegrass peaks at soil temperatures of 60°F and declines sharply as temperatures rise above 70°F. Root growth practically ceases at temperatures above 80°F.

It prefers medium moist conditions though it is resistant to drought. It is extremely hardy, bearing severe frost and a long covering of snow without injury.
http://chestofbooks.com/flora-plants/weeds/Fodder-Pasture-Plants/Kentucky-Blue-Grass-Poa-Pratensis-L.html

How to use Kentucky Bluegrass:

Sport Fields





Cleveland Browns Stadium's famous Kentucky Bluegrass


Beautification

http://www.uri.edu/ce/healthylandscapes/busstop2.htm
"The remaining exposed areas were stabilized with a Kentucky Bluegrass sod. Kentucky Bluegrass is tolerant of heavy traffic and sod is one way to provide a quick, vegetative stabilization of bare areas, serving as a way to minimize erosion and runoff."


"Kentucky Blue Grass. All Organic Lawn. Always cut at the highest setting on lawn mower. Mulch the clippings back to the soil. Organic Fertilizers are the only way to GROW!"


Public Parks

Seeding Rates


SEEDING rates for Kentucky Bluegrasses are 1-3 pounds seeded at 1000 square feet and between 45-135 pounds seeded per acre. Pasture rates can be lower, but even pastures need the thickest stand possible especially in the beginning. Mixes are often seeded at 3-5 lbs per 1000 sq.ft.

http://www.bluegrasses.com/seeding/index.html

Seed with Perennial Rye Grass


Because Bluegrass takes time to germinate and grow into a lawn, often Perennial Ryegrass is an important mix of establishing a Bluegrass lawn. If a pure lawn is desired, keep the % of ryegrass as less than 15% (by weight)

Germination Time


Bluegrass seeds do take longer to germinate (often 4-8 weeks), thus many landscapers also include perennial ryegrass as part of their turf establishment. Generally you should water daily after planting until germination occurs, then continue on a more normal cycle.http://www.bluegrasses.com/seeding/index.html
http://aggie-horticulture.tamu.edu/plantanswers/turf/publications/bluegrass.html

Mowing Requirements


Begin mowing young grass when it grows above a 2-inch cutting height. Either rotary or reel type mowers may be used but blades must be sharp and reels properly adjusted to prevent pulling up young seedlings. The initial cutting should be at a 2-inch height. Subsequent mowings should be frequent enough so that no more than one-third of the leaf is removed at each mowing. At a 2-inch mowing height the grass needs mowing before it reaches 3 inches. Weekly mowing is usually satisfactory at the 2-inch mowing height. At lower mowing heights more frequent mowing is required. Some of the improved bluegrass varieties such as Fylking, Ram I and Touchdown tolerate mowing heights below 1 inch. However, weaker stands of Kentucky bluegrass result when mowing height is below 1 inch. Also, at mowing heights below 1 inch annual bluegrass and crabgrass invade a bluegrass turf. At mowing heights above 1 inch weeds are much less of a problem.

http://aggie-horticulture.tamu.edu/plantanswers/turf/publications/bluegrass.html

4.14.2010

Fertilizer Recommendations


Nitrogen requirements of Kentucky bluegrass are much higher during the establishment year than during subsequent years. The grass will respond to 5 to 6 pounds of nitrogen the first year; whereas, 2 to 3 pounds are adequate for maintenance after the first year. During summer months Kentucky bluegrass will burn if too much soluble nitrogen is applied at one time or if it is not watered in immediately after application. No more than ° pound of soluble nitrogen per 1,000 sq. ft. should be applied in one application. Slow release nitrogen sources can be applied in larger amounts and less frequently.

High Watering Requirements


Compared to the warm season grasses, Kentucky bluegrass has a high water requirement. In summer, as much as 2 inches of water per week are needed to keep bluegrass green and growing. Ideally this amount of water would be applied in one day to wet the entire rootzone of the turf. However, the effective rootzone is often too shallow to hold that amount of water. No less than 1 inch of water should be applied on any single day to promote deeper rooting of the bluegrass turf.