Wednesday, March 23, 2011

FAQ: What's wrong with my centipede lawn?

(I visited the site and took a soil sample to the local Cooperative Extension Service office for testing.)

Your lawn problems are related to shade, mowing height, soil pH, phosphorus and potassium levels, fertilizer, irrigation and soil erosion on the slope. In addition, tree roots are surfacing in the front yard. Sod will not grow over the visible roots.

Centipede grass does best in full sun. Most of your front lawn is shaded. There is nothing that can be done about the shade.

Your grass is cut too short. Centipede grass should normally be cut at a mowing height of 1-1/2" to 2", but due to the shade (lack of available light) the mowing height should be increased to 2-1/2". This provides more leaf surface and allows the sod to make the best use of available light.

Soil pH is too low (4.3). Raise it by applying dolomite (pelletized lime) at a rate of 55 pounds per 1000 square feet.

Phosphorus and potassium levels are too high. Centipede is very sensitive to high phosphorus levels. There is nothing that can be done to reduce the phosphorus and potassium levels. Time will take care of it. Do not use fertilizer containing phosphorus or potassium.

Apply 1-1/2 pounds of 34-0-0 or 1 pound of 46-0-0 fertilizer per 1000 square feet after spring green-up and again in mid-summer. Irrigate immediately after fertilizer application. Irrigate during dry weather to avoid stress.

There is nothing that can be done about the visible tree roots, though some soil could be added to repair eroded areas. If soil is added in the spring, sow annual rye grass to help prevent further erosion.

There are alternatives to maintaining a centipede lawn in difficult circumstances.

The first alternative would be to have the front lawn sodded with St. Augustine grass. St. Augustine is more shade tolerant. Sod roots should be in full contact with soil, so sod should not be put down over surfacing tree roots.

Another alternative would be to grow a more shade tolerant ground cover instead of sod. Trachelospermum asiaticum (Asiatic jasmine), Glechoma hederacea (Creeping Charlie), Ophiopogon japonicus (Mondo) and Herniaria glabra (Rupturewort) would be good choices. Alternative ground covers should be prevented from growing into neighbors' lawns.

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