Lawns Need Fertilizer In August Says LSU AgCenter Horticulturist

Thomas J. Koske  |  7/29/2005 9:05:42 PM

News You Can Use For August 2005

With the heat and humidity of August, we think twice before working outdoors. In wet summers, the extra turf growth and extra mowing also may squelch enthusiasm. But don’t stop, says LSU AgCenter horticulturist Dr. Tom Koske.

August is the last full month you can develop a thick, healthy turf. "In mid-September, believe it or not, the lawn growth slows," the horticulturist says, adding, "At that time you might add some extra potassium as potash to winterize and toughen the turf for winter."

Koske says something he notices a lot in late summer is a loss of general soil fertility in the average lawn. "People fertilize in spring, but forget about it in the hot and humid summer months," he observes.

In average or higher rainfall summers, the neglect can lead to a nutritional shock to the turf that may result in several diseases, such as Take-All Root Rot, Dollar Spot and Curvularia Blight. These diseases seldom occur if the turf is strong.

To strengthen turf, apply a complete fertilizer to all species of warm-season turf grasses. For average lawns, this should have a ratio of high nitrogen (first number of the analysis), low phosphorus (second number) and medium to high potassium (third number). If you can’t find this, apply a 13-13-13 or triple 8 fertilizers so that some N, P and K nutrients are all included. Formulations with some controlled release nitrogen are best at this time.

Centipede, zoysiagrass and carpetgrass are fertilized about one-half pound of N per 1,000 square. feet., but bermuda and St. Augustine grasses receive twice that rate. Most lawn fertilizers recommend the higher rate, so consider the grass you have. This is probably your last application for the year.

The numbers (analysis) on the bag are equal to the percent of that nutrient form in the fertilizer material. For example, in 10 pounds of 10-4-6, are1 pound of nitrogen, 0.4 pound phosphate and 0.6 pound potash. This would be applied at either 5 or 10 pounds of product per 1,000 square. feet. as appropriate for your grass type. With this type fertilizer, a winterizing application of potassium is probably not needed.

"If our bodies get weak and stressed, we can more easily get sick," Koske says, noting, "The same can be said for the sod."

The horticulturist also recommends contacting an extension agent in your parish LSU AgCenter office to learn more about lawn fertility. In addition, look for lawn & gardening and Get It Growing links in the LSU AgCenter Web site:


On the Internet: LSU AgCenter:

On the Internet:

Source: Tom Koske (225) 578-2222, or

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