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Index : Lawns
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- 1. Time To Dethatch Burmudagrass Lawns - Top
- Burmudagrass is the lawn of choice here in Tucson. That's because burmudagrass is a warm season grass well suited to our hot, desert environment. Heat encourages lush, rapid growth, but with it comes the formation of something called thatch.
Thatch is the accumulation of dead grass plants and grass roots. It forms as a layer of brown, spongy material between the green grass and the soil. The faster the grass grows, the more thatch is formed. Eventually, this thatch layer becomes a problem. When it gets thick enough, usually ½ inch or more, it begins interfering with the movement of water and fertilizer. Instead of getting to the roots, water is absorbed by the spongy thatch layer. Plant nutrients, in the form of fertilizer, is also tied up and held in the thatch.
Burmudagrass is a matting type grass that spreads by underground stems called rhizomes, and above-ground stems called stolons. When thatch becomes thick, stolons are forced to grow up above the turf, rather than down along the soil surface. When mowed, the protruding stolons are cut and grass can be scalped as the mower sinks into the spongy thatch.
To determine whether your lawn needs to be dethatched, cut a small hole or plug from the lawn with a shovel. Remove it, roots and all, and look for the brown thatch layer. If it's ½ inch or thicker, it's time to have the thatch removed by verticutting or power raking. July is an ideal month to remove thatch. The hot weather encourages a speedy recovery of the lawn. Never dethatch in the cool weather of fall, winter or early spring!
If you have a small lawn area, and want some good exercise, you can remove the thatch by hand raking it. Special lawn rakes are sold at garden and hardware stores especially for thatch removal. These rakes has heavy, U-shaped tines made for pulling out thatch. Cutting the grass as low as possible prior to raking will make the job easier.
If your lawn is larger, you can rent a motorized dethatcher or power rake. These have vertical rotating blades to cut and pull the thatch out. Dethatching or verticutting should be done in several directions to effectively remove the thatch. Landscape contractor are also available to professionally verticutting services.
Because dethatching is somewhat damaging to the turf, it's important to encourage speedy recovery. This is done by fertilizing with 5 pounds of ammonium sulfate (21-0-0) per 1,000 square feet of lawn area. Fertilization and watering will encourage a quick recovery of the lawn.
Although bermuda thrives in heat, it needs frequent watering. During this, the hottest and driest part of the year, the lawn may need to be watered every other day or every third day. With each watering apply between ½ and 3/4 inches of water. To determine how long to let the irrigation system run, set out straight sided cans randomly throughout the lawn. Let the irrigation system run for a designated period of time and then measure the depth of water in each can. Add the individual measurements up and divide by the total number of collection cans. This will give the average amount of water applied. If the amount is less than ½ inch, increase the length of watering. If the amount is greater than 3/4 inch, decrease the length of watering. Then repeat the test to make sure the system has been properly calibrated.
Dry patches of brown grass often develop at this time of year. It's usually the result of poor coverage by the lawn sprinklers. If certain areas of the lawn are getting insufficient water, adjust the sprinklers to wet those areas. This may require cleaning clogged nozzles and their filters, replacing nozzles with ones that have a greater spray radius, or adding more spray heads.
Sometimes dry spots develop when the soil becomes impenetrable to water. If water sheds off and will not soak into the soil, poke holes in the soil with a pitch fork or screw driver. This should improve water penetration. Soapy water can also be used to wet these water shedding patches. Don't use too much soap. One teaspoon of a liquid dish washing detergent in one gallon of water is sufficient. Wet the dry patches once with the soap solution just before your lawn sprinklers come on. One treatment is all that's usually needed.
Finally, to keep your summer lawn looking it's best, mow it frequently. And whether you use a rotary mower or a reel type, make sure the blades are kept sharp.
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Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona, 520-626-5161.
Material originally appeared in Arizona Daily Star gardening column, on July 5, 1998
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- Updated: July 5, 1998
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