LSU AgCenter's Weekly Message

Taking Care of St. Augustinegrass Lawns

Last week’s article addressed centipedegrass lawn care. Here, I discuss maintenance of one of the other common turfgrasses in our area, St. Augustinegrass.

As I mentioned in the last article, best practices for these two turfgrasses are different. If you have some of both in your lawn and prefer one over the other, you can promote growth of the one that you want by following recommended practices for that turfgrass.

Many people find St. Augustinegrass to be attractive, and it’s one of the best turfgrasses for shady areas. (Even St. Augustinegrass won’t grow well in dense shade, though. If your yard is really shady, a non-grassy groundcover may be a better choice than trying to grow turfgrass.)

While centipedegrass does best in relatively acidic soil (pH 5 – 6), St. Augustinegrass needs a soil pH more like what we’d want in a vegetable garden. A pH within the range of pH 6 – 7.5 is recommended. In many of our yards, lime will be needed to raise the pH to this range.

A soil test is needed to know what the pH of the soil is. If you get a soil test and indicate that you’re growing St. Augustinegrass, a lime recommendation will be given if it’s needed.

St. Augustinegrass needs more fertilizer than centipedegrass for best growth. Fertilizer can be applied at the rate of 1 pound of actual nitrogen (N) per 1000 square feet in both April and June. If more growth is desired, another application can be made in August. The fertilizer can be either readily soluble or slow-release.

For example, if you’re using a fertilizer that has the analysis 16-0-8 (16% nitrogen, 0% phosphate, and 8% potash), you would use 6.3 pounds of this fertilizer per 1000 square feet in April, June, and (optionally) August to get 1 pound of actual nitrogen each time.

For nutrients other than nitrogen, a soil test is needed to know how much (if any) are needed.

One negative attribute of St. Augustinegrass is that it is more prone to getting the disease large patch than some other turfgrasses are. One way to reduce the impact of this disease is to make sure that nitrogen-containing fertilizer is not applied at higher-than-recommended rates and that it’s not applied too early or too late in the year. Also, if you water your lawn, do it in the early morning.

In sunny areas, St. Augustinegrass can be mowed at a height of 2.5 to 3 inches. In shade, raising mower blades to 3 to 3.5 inches leaves the grass with more surface area to intercept light. As with other turfgrasses, mow often enough that you don’t have to remove more than one-third of the total height of the grass when you mow.

If you need to dethatch or aerate, late spring and early summer are typically good times to do this. Soil should be neither too wet nor too dry.

Let me know if you have questions.

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Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).