MASTER GARDENER: Keep it green: Aiken area turf grasses

  • Posted: Sunday, February 23, 2014 12:01 a.m.

This is the first of two articles that deal with the challenge of growing a beautiful lawn here in the Aiken area, a challenge created by environmental factors that include sandy and infertile soils, long periods of drought and a high-humidity climate.

Four turf grasses grow relatively well here in Aiken: centipede, St. Augustine, zoysia and Bermuda. This first article will discuss centipede and St. Augustine, the two types of local turf grasses that are stoloniferous, meaning they spread by lateral stems (stolons) that creep on top of the soil surface.

Both grasses fill in bare spots easily, and are also relatively easy to control around landscape areas and walks because the above-ground stolons are easy to pull or cut.

Centipede grass

Centipede, currently the most common home lawn turf grass in the South, is sometimes called “lazy man's grass” because of its low fertilizer requirements, slow growth and drought tolerance.

A naturally yellow-green colored perennial grass, some homeowners want to fertilize their centipede so its color is a darker green, and this is best done with an annual application of half to 1 pound of nitrogen per 1,000 square feet in early May after the lawn fully greens up. (A soil test will help determine exactly which fertilizer formula you need.)

An unusually yellow appearance may indicate an iron deficiency due to soil temperatures lagging behind air temperatures. Spraying with iron (ferrous) sulfate (2 ounces in 3 to 5 gallons of water per 1,000 square feet) or a chelated iron source will help deepen the green color of your centipede lawn. Disadvantages of centipede grass include an intolerance of foot traffic, potential damage from nematodes and poor cold tolerance.

TifBlair is a highly recommended variety of centipede grass in our area. Available in both seed and sod forms, TifBlair is prized for its cold hardiness, ability to thrive in acidic soils, drought tolerance due to a deep root system and larger seeds that result in a shortened “grow-in time” for seeded lawns.

While being developed for market, TifBlair was tested with varying mowing heights and nitrogen application rates. After only one-year's data, centipede decline was observed in TifBlair maintained at 3 inches and fertilized with either 2 or 4 pounds of nitrogen per 1,000 square feet per year.

In general, plots mowed at 1.5 inches and fertilized with 1 to 2 pounds of nitrogen per 1,000 square feet per year had very acceptable turf grass quality, color and less thatch buildup.

This further illustrates that centipede does not benefit from increased nitrogen applications, and should only be fertilized at a rate of half to 1 pound of nitrogen/1,000 square feet annually. This is why it's called the “lazy man's grass” – it actually performs better when you ignore it.

St. Augustine grass

St. Augustine grass, also known as Charleston grass here in South Carolina, grows best in temperatures between 80 and 95 degrees, and is dormant below 55 degrees. It has large flat stems and broad coarse leaves with attractive blue-green color, and is installed as sod or plugs because of a problem with seed viability. St. Augustine grass is the most shade-tolerant of our area's warm-season grasses, and grows well in sandy soils. It is susceptible to cold injury in severe winters, so we may be seeing some problems with St. Augustine lawns this spring. It's often affected by chinch bugs, which can cause extensive damage, has low drought tolerance and doesn't stand up well to traffic.

General guidelines for turf grass care

You can't grow Southern turf grasses in the shade. When we get calls about failing turf grasses, the culprit most often turns out to be too much shade.

You need at least 6 hours of sun to grow a good-quality lawn, so stop fighting a battle you won't win. Consider expanding your landscape beds, using an alternative ground cover under trees, or removing some bottom limbs from trees to reduce shade.

Get a soil test to determine the fertilizer needs of your turf grass. For specific recommendations on fertilizer applications rates, and details on discussions in this article, visit Clemson's online Home and Garden Information Center at http://www.clemson.edu/extension/hgic/, click on “Landscape, Garden & Indoor Plants,” and then follow the links to the list of bulletins written for lawns. The maintenance calendars written for each type of turf grass are particularly helpful. Determine the amount of fertilizer product needed to apply ½ pound of nitrogen per 1,000 ft² by dividing 50 by the first number in the fertilizer ratio. For example, for a 16-4-8 fertilizer, divide 50 by 16. The result is 3.125 pounds of product per 1,000 square feet: 50/16 = 3.125 pounds of 16-4-8 per 1,000 square feet.

Looking for alternative organic treatments for your lawn? First, and most important, use a mulching mower, and leave the grass clippings on your lawn; those clippings are a great source of nitrogen for all turf grasses.

If clippings begin to clump, they can be collected occasionally and used as mulch or added to your compost pile. Second, consider adding a ¼-inch layer of top dressing to your lawn in the spring using a high-quality compost and sand mix that is free of weed seeds.

The top dressing of organic material will improve the health of your soil, and therefore improve the health of your turf grass. Finally, the use of slow-release organic fertilizers can be beneficial for your turf grass.

These natural fertilizers are not suspended in salts, are broken down slowly by microbes in the soil, and are less harmful to humans and the environment. As always, get a soil test to determine the fertilizer needs of your yard or garden.

If you have questions about caring for your turf grass, or other garden topics, call the Aiken Master Gardeners at 803-649-6297 ext. 122; send an email to info1@aikenmastergardeners.org; or visit the office at 1555 Richland Ave. E.

The Master Gardeners will hold its first Meet a Master Gardener event at the Aiken Farmers Market from 8 a.m. to noon on Saturday. We will answer your lawn and garden questions, and also present a special demonstration on composting, including small-scale composting using your kitchen scraps, and making your own compost tea.

Pam Glogowski moved to Aiken in 2001 from Janesville, Wis., and has been an active Master Gardener volunteer since 2007.

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