Proper maintenance practices are essential in order to produce an attractive, healthy centipede grass lawn.
Fertilization - A fertilization program should be based on soil test analysis. Centipede has a natural light green color and is suited to acid soils (pH 5.0 to 6.0) but grows best at a higher pH. High rates of fertilizer, especially nitrogen, will produce a dark green color but will also lead to growth problems. One to two pounds of nitrogen per 1000 square feet per year is generally good for centipede, although it will grow well without any fertilizer. Apply nitrogen in split applications. Apply the first two to three weeks after spring green-up and the second in midsummer (July - August). Determine phosphorus and potassium needs by soil testing. If soil testing is not used, a general recommendation would be 4 pounds of 16-4-8 per 1000 square feet after spring green-up and again in midsummer. Apply the fertilizer evenly over the area when the grass leaves are dry. Remember, avoid excessive fertilization and avoid early spring applications.
Mowing - Proper mowing is also very important to maintaining healthy, attractive turf. Mow at 1 to 1-1/2 inches. Use a rotary mower with sharp blades, and mow often
enough so only 1/3 of the plant height is removed. High and infrequent mowing tends to encourage thatch development, which can lead to chlorosis, drought stress and winter injury. However, during periods of moisture stress or in shaded areas, the mowing height should be raised about 1/2 inch.
Irrigation - Irrigate during periods of moisture stress to keep centipede healthy. Water only when the grass shows signs of moisture stress, such as rolling leaves, gray color or wilting. Apply enough water to thoroughly wet the soil to a depth of 6 to 8 inches. Early morning is the best time to water, since evening watering can encourage disease development.
Irrigation during the fall and spring can be very helpful to centipede grass. Although the grass is not totally green, it is still growing at this time. Therefore, it should receive some water either from rainfall or irrigation every two weeks. This may be particularly important in the spring as new shoot and root growth begin.
Centipede is susceptible to yellowing or iron chlorosis. The chlorosis may be caused by one or more of the following factors:
1. Excessive nitrogen or nitrogen applied during spring green-up.
2. High soil pH, phosphorus or potassium levels.
3. An excessive thatch caused by over-fertilization, irrigation or pesticide use, or by poor mowing.
Iron chlorosis can be temporarily overcome by spraying 2 ounces of ferrous sulfate per 1000 square feet or a chelated iron material according to label rates. An excessive application of iron will appear within a few hours as blackening of the leaves. The grass may take a few weeks to fully recover from such high rates of iron. However, the real solution is to determine and correct the cause of chlorosis.
Thatch - Thatch is a layer of dead plant material that accumulates on the soil surface. If centipede is properly fertilized, mowed and watered, grass clippings will not promote excess thatch accumulation. In fact, returning the clippings to the soil will recycle plant nutrients. The stolons of centipedegrass are very resistant to decomposition and often grow on top of each other. When fertilized excessively, rapid stolon growth often leads to thatch accumulation. Where the thatch layer exceeds 1/2 iinch in depth, the lawn become "soft" and "spongy." This excess thatch reduces water movement, encourages shallow rooting, and often results in winter injury.
Removing the excess thatch is generally a gradual process that may be done before spring green-up or between green-up and the summer dry period in July. Use vertical mowers, aerifiers, power rakes or other dethatching equipment to remove the thatch. Vertical mowers should have blades 2 inches apart, since closer blade spacing removes too much turf and reduces recovery rate. Also, more than one pass over a centipede lawn removes too much plant material and reduces the lawn's recovery rate.
Topdressing once or twice a year with 1/4 inch layer of topsoil is the most effective method of thatch reduction but also the least practical cultural practice because of the cost of specialized equipment, topsoil and labor. Discourage thatch development by avoiding excessive fertilization.