Fertilizers for Centipede Grass

Centipede grass is a common choice of turf for lawns in the southeastern U.S. It requires little maintenance compared to some other grasses, and offers good warm-season color. But low maintenance doesn't mean maintenance-free: a centipede lawn still needs to be fertilized each season. Fertilization done right can help you achieve a lush lawn. Fertilizer applied incorrectly, however, can cause more harm than good.

When you apply fertilizer to a centipede lawn is as important as what you apply. Centipede grass should be fertilized twice per year, in May (or after spring green-up) and again in midsummer. The idea is to feed your grass during its season of active growth, giving it just what it needs and no more. If you err on the frequency of application, do less rather than more. Over-fertilizing can lead to problems such as thatch, which will ultimately cause your centipede lawn to struggle and die in patches.

The only way to know the nutrient needs of your lawn with any degree of certainty is by performing a soil test. This is a simple process that can be done through your local agricultural extension office. Obtain a test kit from the agency and fill the provided container with a sample of soil from your lawn according to the enclosed directions. The sample is then sent to a soil lab, typically at a regional university, for testing. The lab will then mail to you a report analyzing the nutrient content of the soil and offering recommendations for what should be applied to maximize its richness for your intended purpose. With centipede grass, the key number you should heed is the nitrogen recommendation.

There are many brand names of fertilizer on the market, but all are labeled with three numbers that tell you the nutrient content of the product. The first number is the nitrogen content, and the most important for centipede grass. For instance, in a fertilizer labeled 16-4-8, the 16 indicates the nitrogen content. The back of the package will include the manufacturer's recommendation for application rates, usually expressed in pounds per 1,000 square feet of lawn. Many products also include a guide to settings on your broadcast spreader to achieve the proper distribution.

If you have a recommendation from your soil test, compare the two and adjust the application rate to meet your lawn's specific needs. If you don't have access to that information, aim for no more than 2 pounds of nitrogen per 1,000 square feet of lawn annually. This can be divided into two applications of 1 pound each. If in doubt, use less fertilizer rather than more, since over-fertilizing is more damaging than under-fertilizing.

Another key need of your lawn with regard to the soil beneath is a good pH balance. The ideal pH for a centipede lawn is 6.0, and your soil test results should recommend the quantity of lime needed to achieve that. If you don't have a soil test, 25 pounds of lime per 1,000 square feet of lawn is a good rule of thumb. Liming can usually be saved as a once every two or three years project, unless your soil test suggests otherwise.

Some lawn experts recommend choosing a phosphate-free fertilizer on centipede grass, as phosphorous can deplete iron levels in the soil, leaving your pH too high and your grass an unattractive yellowish color. The phosphorous content of the product is the second number in the three-number label, so a 15-0-15 fertilizer is phosphate-free.

You may also want to steer clear of weed-and-feed products for centipede, because the application timing for the two components involved is different for this type of grass. Pre-emergent weed killer is designed to be applied before spring green-up --- before weeds have a chance to germinate --- but fertilizer shouldn't be applied to centipede until after green-up, later in the spring.