Tony Bertauski: How to keep your centipede grass lawn lush this summer
Warm-season turfgrass has recovered from winter dormancy. While there are several types of grass for lawns, most people have centipede grass because it's inexpensive and low-maintenance. Here are some tips to keep your centipede lawn healthy.
Nitrogen boosts growth and improves color, but centipede grass prefers lower amounts of nitrogen compared with other turfgrasses. General recommendations are to apply ˝ to 1 pound of nitrogen per 1,000 square feet in May and again in August. Exceeding these applications can result in long-term problems.
While dark green typically is associated with higher quality, centipede grass is naturally Granny Smith Apple green.
Efforts to darken the color with heavy applications of nitrogen can lead to problems, especially in the fall. However, iron can improve color without affecting growth. This would be ideal in early spring and late fall.
Potassium is the stress nutrient, making turf more tolerant of drought and temperature extremes. In the Lowcountry, potassium is frequently deficient in soil. An ideal fertilizer would be slow-release containing equal parts nitrogen and potassium and little to no phosphorus, such as a 15-0-15.
A soil test will reveal pH problems and nutrient deficiencies. If pH is low, it will affect the availability of certain nutrients regardless of the quantity in soil, in particular minor nutrients such as iron.
Low pH is easily remedied with an application of lime.
A soil test will recommend a lime application rate. Mix a pint of soil from several different parts of the yard about 6 inches deep. Samples can be taken to the Clemson Extension office at 259 Meeting St. Call 722-5940.
Thatch is a spongy layer of undecomposed organic matter that accumulates on top of the soil. It is mostly composed of stolons and rhizomes. Clippings do not contribute to thatch because they are mostly water.
Returning the clippings will not affect thatch and allows nitrogen to return to the soil. Burning dead topgrowth in late winter also does not reduce thatch.
Thatch layers thicker than ˝-inch make centipede grass more susceptible to environmental stress and disease. High nitrogen applications are one of the major causes of excessive thatch. Core aerification is an effective treatment.
Aerifiers punch holes in the soil, which physically removes thatch while stimulating root growth and microbes that feed on thatch. This process can be done anytime of the year. Core aerifiers can be leased from local equipment rental dealers.
Dethatchers, or vertical mowers, cut lines in the lawn that rip thatch out of the ground and stimulate horizontal growth. It's effective but much more stressful on the lawn than aerifying. Dethatching is generally recommended during spring to allow recovery before the stress of summer heat.
Be sure that the mower blade is sharp for a quality cut. Most sources recommend 1.5 to 2 inches as an ideal mowing height for centipede grass. A higher mowing height will have the advantage of a deeper root system to better handle summer stress.
Allowing it to grow a little higher several weeks before expected frost helps store additional carbohydrates for the winter.
Centipede grass is susceptible to brown patch disease in late summer/early fall and again in spring. It is likely to occur in damp, shady conditions.
Nitrogen can exacerbate brown patch, so cut back on fertilizer in these areas. Brown patch appears as dying spots that are a couple of feet in diameter. Granular fungicides can be used to prevent or treat infected areas.
While there are insects that feed on centipede grass, such as mole crickets and armyworms, they can be treated on an as-needed basis.
A soapy flush (1 ounce of dish soap per gallon) can be used to bring insects to the surface to verify they are causing damage.
Centipede grass will handle a moderate amount of shade and traffic. However, St. Augustine is the best shade grass. A new bermuda grass called Tifgrand is supposedly very good in shade as well.
Tony Bertauski is a horticulture instructor at Trident Technical College. To give feedback, email him at email@example.com.