Fertilize in August Horticulturist Recommends

Thomas J. Koske  |  10/4/2004 4:24:24 AM

Distributed 7/25/03

As we move into August, heat and humidity make you think twice before working outdoors. In wet summers, the extra turf growth and extra mowing also may squelch your enthusiasm. Don’t stop! says LSU AgCenter horticulturist Dr. Tom Koske.

August is the last full month you can develop a thick, healthy turf. "In September, believe it or not, the lawn growth slows," the horticulturist says, adding, "At that time you might add some extra potassium 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 late-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. With strong growing turf, these problems seldom occur.

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. Controlled release formulations are best at this time.

Centipede and carpetgrass are fertilized at about one-half pound of N per 1,000 sq. ft., but bermuda, zoysia and St. Augustine grasses receive twice that rate. 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, is 1 pound of N, 0.4 pound P and 0.6 pound K. This would be applied at either 5 or 10 pounds of product per 1,000 sq. ft. as appropriate for your grass type.

"If our bodies get weak and stressed, we can 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. For more information, you can also visit the Gardening and Get It Growing sections of the LSU AgCenter website.

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