Soil can have a dramatic effect on the color, growth rate, and overall health of your Centipede grass lawn. One particular soil measurement, soil pH, is especially important in dealing with Centipede grass lawns. Soil pH is measured on a scale of 0-14 with 7 being neutral. A soil pH below 7 is considered acidic while a soil pH above 7 is considered alkaline. Centipede grass lawns prefer a soil pH between 4.5 and 5.5, which is lower than other lawn grasses. We can manipulate soil pH by applying lime to raise the pH and elemental sulfur to lower pH. Since most soils in the South are naturally acidic, we can often grow centipede grass without having to change the soil pH. As a rule,, your soil pH will not be too acidic for a centipede grass lawn and you should never apply lime.
The best way to determine the exact pH of your soil is to have soil test done by your local cooperative Extension agency. If your soil pH is above the preferred range for Centipede grass, the soil test results will recommend the amount of elemental sulfur needed to lower pH to the acceptable range. Again, you can safely assume that your soil will never be too acidic for a centipede grass lawn. Do not add lime.
Problems with Light Green or Yellow Centipede Grass
Centipede grass lawns are naturally light green and will never achieve the dark green hue of a zoysia grass or fescue lawn. All too often we look at a centipede grass lawn and think it needs to be fertilized when it is actually growing at its optimal color. This is especially dangerous since excess nitrogen application can cause centipede grass growth problems.
Centipede grass lawns can, however become an abnormal yellow-green. This may be caused by one of several reasons. First, it could be chinch bugs. Pound a coffee can in the yellow turf as described in the "Insects and Pest" section. If you do not find chinch bugs, the problem is probably chlorosis. Centipede grass chlorosis is usually caused by an iron deficiency in soil with high pH (6 or above). You can correct an iron deficiency in one of two ways. First, you can spray with liquid iron for a short term cure. Iron will help the centipede grass to return to its natural green within a week or so. The darker color will late, however, for only about 4 weeks. Better yet, you can correct the iron deficiencies by lowering the pH to the 4.5 to 5.5 range with elemental sulfur product. As you lower the pH, iron that is already in the soil will become available to the grass. The most common form of elemental sulfur is aluminum sulfate. It is usually available in 50 lb bags and should be applied at the recommended rate on the bag.
Occasionally, centipede grass lawns develop iron chlorosis because they are growing in compacted or soggy soil that is low in oxygen. You may see this problem in a low spot of the lawn near a surface drain. In these situations grass roots have trouble absorbing iron from the soil. The best way to fix this problem is to correct your irrigation and add extra drainage if necessary. Compacted soil should be aerated using lazyman liquid gold or done with a core aerator.
Links Regarding Maintaining a Centipede Grass Lawn
Centipede Grass Seed