Centipede grass for Florida lawns

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Centipede grass [Eremochloa ophiuroides (Munro) Hack.] was introduced into the United States from southeastern Asia. It is well-adapted to the climate and soils of central and northern Florida and is the most common home lawn grass in the panhandle of Florida.

Centipede grass is a slow growing, low maintenance grass with low fertility requirements. The turf grows close to the ground, is medium-textured and is naturally pale green in color. Over fertilizing to obtain an unnatural dark green color reduces its cold tolerance, increases long-term maintenance problems, and is believed to contribute to "centipede grass decline."

Advantages

Centipede grass does very well in acidic and infertile soils. It has fair to good shade tolerance and good drought tolerance. It can be established from seed, sod, or plugs and spreads by stolons. Maintenance and fertility requirements are low compared to other turf grasses.

Disadvantages

Centipede grass is highly susceptible to damage from nematodes, particularly ring nematodes. This damage limits the use of centipede grass in south Florida's sandy soils. It is also subject to attack from insects called ground pearls. It has a naturally pale green color and is prone to iron chlorosis. It has poor salt, wear, and freezing tolerance.

Stolons from centipede grass have a high lignin content and contribute to a heavy thatch layer, particularly under high fertility rates. The grass is often subject to "centipede grass decline," for which a causal agent has not yet been identified. The decline is influenced by management practices and is enhanced under high fertility, high irrigation, and low mowing height regimes.

Intensive management over a period of 4 to 5 years results in root dieback in the spring. This condition is aggravated by thatch accumulation, which results in new stolons growing several inches above the soil surface. Proper management, with an emphasis on maintenance of a viable root system, is the best solution to this condition. This includes irrigation during drought stress, maintaining a mowing height of 1 1/2 - 2 inches, prevention of thatch accumulation, and adherence to low fertility rates.

Varieties

Common

This is a low-maintenance cultivar that can be established by seed or vegetative means. It grows slowly and in a prostrate manner.

Oaklawn

This improved cultivar has better cold tolerance than Common. It must be established vegetatively.

Centennial

This cultivar was also selected for cold tolerance. Like Oaklawn, it requires vegetative establishment, but is more tolerant of alkaline soils than Oklawn or Common.

Tifblair

This cultivar was released by the University of Georgia in 1997. It has good cold and freezing tolerance, and can be propagated by seed or vegetative means. It has a slightly faster rate of growth than other centipede grass cultivars.

TennTurf

Released by Tennessee in 1999, this cultivar has the best cold tolerance of any centipede grass. It is currently available only as sod, sprigs, or plugs. It prefers full sun but will tolerate some shade. 

Maintenance of Centipede grass

Centipede grass is established by seed, plugs, sprigs, or sod. Planting centipede grass as sod will produce an instant lawn that will establish more rapidly and be less susceptible to various stresses. Lay the sod in a well-prepared seedbed, fitting the pieces tightly together to avoid cracks in the turf.

Wet the Centipede grass soil surface thoroughly prior to laying the sod. After the sod is in place water thoroughly and roll with a lightweight roller to ensure firm contact between the sod and soil. The entire area should be watered daily with 1/2 inch of water per application.

Once the sod has rooted into the soil, irrigation frequency can be reduced to an as-needed basis. Although sodding is more expensive than seeding or plugging, good quality, weed-free sod will produce the best quality lawn. 

Seed of centipede grass is expensive, but the seeding rate is low and this method of establishment is probably cheaper than vegetative planting if time and labor are considered. The suggested seeding rate is 4 ounces per 1000 square feet. The best time to seed is during the period from April to July, since this permits a full growing season before winter weather.

Fall seeding is undesirable because the young seedlings may not become sufficiently established to withstand cold injury during the winter. Centipede grass seed is naturally slow to germinate, and may take up to 2 to 3 weeks. Soil washing due to heavy rain or excessive irrigations should be minimized by lightly mulching the planted area.

Seed quality should be considered when purchasing seed for planting. Insist on seed with a purity of 90% or better and a minimum of 85% germination. Plugging or sprigging centipede grass will leave open areas of soil, which are subject to invasion by fast growing, opportunistic weed species. Due to the slow growth habit of centipede grass, diligent weed control measures will have to be used if this method of planting is used.

The best time to establish centipede grass is during the spring or early summer months. This will enable the grass to grow in before cooler weather begins, when growth will be reduced. Seed may safely be sown until later in the year, but growth will again be greatly reduced in the fall.

When establishing any grass, it is important to provide irrigation more frequently than is normally recommended. Until a viable root system is established, turf demands for irrigation are greater. It is also important not to now until the roots have had a chance to work down into the soil and establish themselves there. 

Proper site preparation before planting is critical to ensure successful establishment. Refer to the chapter on "Preparing to Plant a Florida Lawn" for complete information. Centipede grass is best adapted to a soil pH of 5.0 to 5.5. Severe iron chlorosis may occur if pH is above 6.5 to 7.0.

Preplant application of wettable sulfur at the rate of 430 pounds per acre (10 pounds per 1000 square feet) can be used to lower the pH of some Florida soils 1 pH unit. Do not apply more than 10 pounds per 1000 square feet of wettable sulfur per application. Where more is required, allow 60 days between applications. Irrigate with 1 inch after each application to activate the sulfur. Lime is seldom required for centipede grass.

Fertilizing

Proper fertilization of any lawn grass is an important component of the best management practices of your home lawn. Fertilization and other cultural practices can influence the overall health of your lawn, and can reduce its vulnerability to numerous stresses, including weeds, insects, and disease. 

It is advisable for homeowners to have soil tests done annually. Your local Cooperative Extension Service office has recommendations and bags for taking soil samples and submitting to the Extension Soil Testing Lab for analysis. In particular, phosphorous levels are best determined by soil testing. Since many Florida soils are high in phosphorous, little or no phosphorous may be needed for satisfactory lawn growth. 

Established centipede grass lawns have very low fertility requirements. Centipede grass is a low-maintenance turf grass and does not respond will to excessive use of fertilizer, especially nitrogen. Do not over fertilize centipede grass with nitrogen to equal the color of St. Augustine grass. Over fertilization of centipede grass can result in centipede grass decline, insect pressure, and thatch accumulation.

As with any lawn grass, do not apply more than 1/2 lb. of water soluble nitrogen per 1000 square feet at any one time. Up to 1 lb. of nitrogen per 1000 square feet may be applied at one time, but at least 50% of that nitrogen should be in a slow-release form.

In general, two weeks following spring regrowth, apply a complete fertilizer such as 16-4-8 at the rate of 1/2 (water-soluble) to 1 (slow-release) pound of nitrogen per 1000 square feet. The three numbers refer to percent nitrogen, phosphorus, and potassium, respectively, in the bag.

For example a 50-pound bag of 16-4-8 contains 16% nitrogen or 8 pounds total nitrogen. This bag will fertilize 8000 square feet at the rate of 1 pound of nitrogen per 1000 square feet. University of Florida guidelines for lawn grass fertility show a range of fertilizer rates over which a particular species may be successfully grown for various areas of the state. These ranges are included to account for individual homeowner preferences for low-, medium-, or high-input grass.

Additionally, localized micro-climate effects can have a tremendous effect on turf grass growth, and a range of rates provides more opportunity to allow for these environmental variations. An example of this would be a typical home lawn that is partially shaded and partially sunny. The grass growing in the shade should receive lower rates of fertilizer than that growing in full sun.  

All rates are in pounds of nitrogen per 1000 square feet. For questions on how to apply these amounts, refer to the section in this book entitlited Florida Fertilization. Fertilizer should be applied to centipede grass in 1 to 3 applications for spring greenup through fall.

Do or apply nitrogen too early in the growing season, particularly in north Florida, or subsequent frosts may damage the grass. Likewise, don't fertilize too late in the year, as this can slow regrowth the following spring. If applying water-soluble forms at the lower application rate, it will take more applications to apply the total amount of fertilizer needed for the year than if applying a slow-release fertilizer form. 

As mentioned previously, one of the common problems of centipede grass is a yellowing called chlorosis, which is usually caused by iron deficiency. This condition is most severe where soil pH is high (above 6.5) or where the soil contains large quantities of calcium or phosphorus. This yellowing is generally most severe in early spring, when daytime temperatures are warm but nighttime temperatures are still cool.

Warm daytime air temperatures promote leaf and stolon growth, but cool nighttime temperatures limit root growth. The roots then cannot assimilate enough nutrients to supply the growing leaves, and the leaves turn yellow. As soils become warmer, this temporary nutrient deficiency disappears.

Avoid using excessive phosphorus fertilizers unless soil test results indicate to do so. Iron chlorosis can be controlled by several methods. Soil pH can be lowered by regular use of acid-forming fertilizers such as ammonium nitrate or ammonium sulfate. These will render the iron more available to the grass. If the soil is naturally iron deficient, iron fertilization is necessary.

Centipede grass usually responds well to supplemental applications of iron. Chelated or ferrous sulfate iron can be applied evenly and easily with a hose-end applicator. Apply the ferrous sulfate at the rate of 2 ounces in 3 to 5 gallons of water per 1000 square feet.

Consult the label for chelated iron rates. Fertilizers containing iron and a combination material of ammonium sulfate and ferrous sulfate are also available.

Do not apply nitrogen too late in the growing season, as this can slow regrowth the following spring. A general guideline for the last fertilizer application is mid-September for north Florida, early October for central Florida, and late October for south Florida. It is possible to apply potassium at a rate of 1 pound of potassium per 1000 square feet. This will help the grass to overwinter, tolerate cold temperatures, and green-up quickly in the spring.

Mowing

Proper mowing practices are necessary to keep any lawn healthy and attractive. Centipede grass that is actively growing should be mowed every 7 to 14 days at 1.5 to 2 inches in height. Mowing at this height promotes a deeper, more extensive root system that enables the grass to better withstand drought and nematode stress.

Remove no more than 1/3 of the height of the leaf blades with any mowing (e.g., for a lawn to be maintained at 2 inches in height, mow when the turf reaches 3 inches). It is important not to mow centipede grass at lower heights, as that will reduce the tolerance of the grass to heat, drought, nematodes, and many other stresses. It will also suppress root growth. 

Clippings should be left on the ground after mowing. They do not contribute to thatch build-up, as is often assumed, but are actually readily degraded by microorganisms. They also provide a source of nutrients to the lawn, and can reduce fertility requirements if left on the lawn on a regular basis. A sharp and well-adjusted rotary or reel mower should be used.

Watering

Irrigation on an as-needed basis is an excellent way to water any grass, provided the amount of water is applied when needed. Irrigation is needed when leaf blades begin to fold up, to actually wilt, to turn blue-gray in color, or when footprints remain visible after walking on the grass. Apply 3/4 inch of water per application, which will apply water to the top 8 inches of soil, where the majority of the roots are.

To determine rates from a sprinkler system, place several coffee cans throughout the irrigation zones to find out how long it takes to apply 3/4 inch of water. During prolonged drought, irrigation may be needed more often. Centipede grass has good drought tolerance and will usually recover from severe drought injury soon after rain or irrigation. Do not over water centipede grass lawns as this weakens the turf and encourages weeds.

During extended periods of drought, centipede grass may go dormant if left unirrigated. The grass will turn brown and stop growing during this dormant period, but will revive and resume growth upon irrigation with sufficient amounts of water. 

Information provided by the University of Florida's IFAS Extension