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| HOME: TYPES OF GRASS |
Kentucky Bluegrass Perennial Ryegrass Tall Fescue Fine Fescues Other Grasses Seed Mixtures/Blends Site Preparation Sod Sources in Idaho Main Nutrients How Much to Apply When to Apply What Kind of Fertilizer How to Apply Mowing Height How Often Should I Mow? Clippings Mowers & Maintenance Type of Grass Time of Year/Weather Conditions Type of Soil Sprinkler Systems Billbugs White Grubs Earthworms Diseases Weeds Thatch Prevention Thatch Removal/Managment |
Not
all grasses are created equal. In Idaho, most home lawns are composed
of Kentucky bluegrass, perennial ryegrass, tall
fescue, fine fescue or a combination of the four.
These grasses are classified as cool-season turfgrasses and are well
adapted to northern regions of the U.S. They grow rapidly in the spring
and fall when soil temperatures are around 55 - 65o F. Their growth
is slower
in the summer as both air and soil temperatures rise (Figure 1). These four grasses differ in their adaptation to shade and cold temperature, as well as in their color, texture, maintenance requirements, and growth habit. The growth habit of lawn grasses affect how quickly they can spread into bare areas. Bunch type grasses grow in clumps and spread very slowly by tillers which are secondary stems that grow vertically from the base of the plant. In addition to tillers, spreading type grasses produce stems that grow horizontally either underground (rhizomes) or aboveground (stolons). Grasses with these types of stems can fill in bare or damaged areas much more quickly than bunch-type grasses. The following link provides a detailed overview of grass growth with excellent visuals: www.ahnrit.vt.edu/portfolio/howgrassgrows/howgrassgrows.swf So which grass should you plant if you are establishing a new lawn, renovating or re-seeding an existing lawn? Unfortunately, the answer is, "it depends." There are many important factors that need to be taken into consideration such as the intended use of the lawn, the amount of care it will receive, and the environment. Will it be a showcase lawn for the neighbors to admire, or will it be the type of lawn that violates your subdivisions landscape covenants? Do you have pets? Will you have lots of BBQs and foot traffic on the lawn? Once you have determined the quality level and intended use, you can choose the grass best suited to your specific needs. Even if you already have a lawn established it is important to know what type of grass you have so that you can fine tune your management practices to best suit the needs of that particular grass. The following section describes the four most common lawn grasses in Idaho including information about adaptation, identification characteristics, growth habit, advantages, disadvantages, management considerations, and variety selection. Kentucky bluegrass Kentucky bluegrass is the most widely adapted and most commonly used lawn grass in the United States. It does well in sunny areas throughout Idaho, is very cold tolerant, and will form a dense, high quality turf when grown in full sunlight. The leaves have a characteristic boat-shaped leaf tip and a prominent midrib (Figure 2).  A.  B. Figure 2. A. Boat-shaped leaf tip of Kentucky bluegrass. B. Midrib on top of leaf surface. (Photo Courtesy: A.J. Turgeon, Penn State University) Kentucky bluegrass has a spreading growth habit with aggressive rhizomes allowing it to form a dense sod and fill in bare spots quickly during establishment. These rhizomes also make it challenging for gardeners striving to keep this growth from creeping into adjacent flower beds. Additionally, this aggressive, spreading growth habit makes Kentucky bluegrass susceptible to thatch [hotlink] development especially under high fertility and moist conditions. Yearly aerification [hotlink] and prudent fertilization and irrigation practices will help keep thatch to a manageable level. A major limiting factor of Kentucky bluegrass on home lawns is its lack of shade tolerance. Under heavy tree shade or on the north sides of houses that receive substantial shade during the day, it will thin and develop powdery mildew [hotlink], a white, powdery fungus on the leaves. Raising the mowing height in shady areas will help some, by giving it more leaf area to catch light. Kentucky bluegrass requires medium to high inputs of water and fertility depending on the desired quality level of the lawn. For most home lawns, Kentucky bluegrass should be maintained at a mowing height of 2 - 3.5 inches. Mow towards the higher end of the range to develop a deep root system. Kentucky bluegrass requires 2 - 5 lbs of nitrogen (N) per 1000 ft2 per season. Irrigation requirements will range from 1 - 1 1/2 inches per week in the spring to 1 1/2 - 1 3/4 inches in the summer. Kentucky bluegrass will tolerate extended periods of drought by going dormant as long as it is allowed to properly harden prior to the drought. Establishment from seed can be quite slow, requiring upwards of 10-20 days for germination. Using a straw mulch or a mixture with a small percentage of perennial ryegrass which germinates much faster, will provide some protection to the slower germinating Kentucky bluegrass seedlings. Planting sod will bypass this germination problem, but proper care during sod grow-in is just as important as with seed establishment. Kentucky bluegrass sod is readily available in Idaho from garden centers and directly from sod producers. There are many varieties of Kentucky bluegrass available giving a wide range of disease resistances, wear tolerance and green color. Most of the grass seed available at your local garden center or lawn & garden areas of major chain stores will have varieties of superior quality. Just make sure and check the label on back of the seed package to insure that you are buying 'named' varieties and not 'variety-not-stated'. Named varieties listed on the label indicate that the variety(ies) is an improved variety and has gone through several years of testing. It is best to choose a blend of three or more Kentucky bluegrass varieties to insure a broad resistance base to diseases. The following fact sheet from Colorado State University outlines the positive and negative characteristics of Kentucky bluegrass as well as provides some management considerations: www.csuturf.colostate.edu/pdffiles/KBG%20fact%20sheet%20for%20homeowners.pdf 
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Perennial Ryegrass Perennial ryegrass is a bunch-type lawn grass that is commonly used in grass mixtures with Kentucky bluegrass on home lawns and sports fields. It is very similar in color and appearance to Kentucky bluegrass (Figure 3).  A.  B. Figure 3. A. Pointed leaf tip of Perennial ryegrass, and B. Glossy bottom of leaf and veiny leaf upper surface. (Photo courtesy: A.J. Turgeon, Penn State University) The leaves of perennial ryegrass do not have the boat-shaped leaf tip like Kentucky bluegrass, instead they have a pointed tip and their veins on the top side of the leaves are very conspicuous. The veiny leaves make perennial ryegrass difficult to mow especially if mower blades are not kept sharp. This leaf characteristic is also what gives perennial ryegrass the traffic tolerance for use on sports fields. Perennial ryegrass is not as cold hardy as Kentucky bluegrass and is more prone to winter kill than Kentucky bluegrass. Perennial ryegrass is considered a short-lived perennial because of this lack of cold tolerance and it is not recommended in the higher elevations of Idaho, but will do very well along the lower Snake River plains. Perennial ryegrass germinates from seed considerably faster than Kentucky bluegrass and can overwhelm the other grasses in a mixture if there is too high of a percentage (over 20%). Perennial ryegrass will not fill into bare or damaged areas as quickly due to its bunch-type growth habit. It also does not form thatch due to its lack of rhizomes. Perennial ryegrass is slightly more shade tolerant than Kentucky bluegrass, but may thin out in shaded areas over time due to its lack of storage organs. It is also fairly drought resistant since it can develop a deep root system Perennial ryegrass requires medium to high culture and should be mowed between 2 - 3 inches. Remember to keep mower blades sharp to cut through the tough leaves. Fertility and irrigation requirements are similar to those of Kentucky bluegrass. Sod is not available as pure perennial ryegrass, but many sod growers use perennial ryegrass in a mix with Kentucky bluegrass. Establishment of perennial ryegrass from seed is relatively easy due to its very quick germination rate. Seed at rates of 6-8 lbs per 1000 ft2. As with Kentucky bluegrass, many good quality varieties are available at garden centers. Make sure to avoid selecting grass mixtures with annual bluegrass, as this grass gives a poor quality turf over time and should be used for quick, emergency use areas only to hold soil from erosion. Make sure and select 'named' varieties.
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Tall Fescue Tall fescue, like perennial ryegrass, is a bunch type grass with a slightly coarser leaf texture than Kentucky bluegrass and perennial ryegrass, however, many turf-type 
Figure 4. Tall fescue lawn. (Photo: T.A. Salaiz University of Idaho) varieties with much finer leaves are now available. Tall fescue is gaining popularity on home lawns and is used on sports fields because of its tough leaves which give it good traffic tolerance.
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