Dethatching Centipede Grass

Centipede grass is a warm-season turfgrass that’s prone to excessive thatch buildup due to over-management and slow-decaying thatch matter. Thatches do prevent your centipede grass lawn to look at its best. 

Dethatching centipede grass is necessary to lower its vulnerability to extreme temperatures, drought, and diseases. However, it should be done with caution, as aggressive dethatching tools can cause excessive turf injury or even die back. Dethatching centipede grass is best done by use of a hand/power rake, vertical lawnmower, and biological dethatching liquid.

Here’s how to manage thatch to make your centipede grass lawn the best version of itself. 

Should you dethatch centipede grass?

Centipede grass thatch consists of dead shoots/stolons, shed roots, and other organic matter on the lawn. You should dethatch centipede grass since thatch makes lawn soil more acidic, which is detrimental to the growth of centipede grass. Thick layers of thatch also form a barrier that prevents fertilizer and herbicides from reaching the soil below.

Another reason why you should get rid of thatch in centipede grass is that new grass forms roots in the thick thatch layer rather than the soil. Such shallow-rooted grass is more vulnerable to heat, cold, and drought conditions. Finally, thick thatch forms a great habitat for disease-causing insects and microbes.

Note: Studies have also shown that thatch buildup in centipede turfs causes ‘centipede decline’, a condition whereby centipede grass fails to green up in the spring.

Centipede grass readily forms thatch from its dead stolons, leading to thick thatch buildup. Stolons are the above-ground runners through which centipede grass spreads. The high lignin content in the stolons doesn’t allow thatch to break down easily. Therefore, they form a thatch layer between the centipede lawn and the soil.

Centipede grass doesn’t need as much fertilizer as other types of turf grasses – hence the name ‘Lazy man’s grass. It only needs two pounds of nitrogen per 1000 square feet annually. Over-fertilization makes it form thatch. Overwatering the lawn and letting the grass grow taller than two inches before mowing also encourages excessive thatch buildup on centipede turfs.

How do you get rid of thatch in centipede grass?

Dethatching is best done when the soil is moist. As such, irrigate it 2 days prior to dethatching to prep your centipede lawn for dethatching. Then, use a hand leaf rake, a power rake, a vertical lawn mower (verticutter), or a dethatching liquid to effectively get rid of thatch in centipede grass. 

Use a hand leaf rake

The simplest way to get rid of excessive thatch buildup on centipede grass is by vigorously raking the lawn using a hand leaf rake. The tines of the rake will pull out the thatch from below the grass blades to the top of the lawn. Note that hand rakes are less invasive than power dethatching tools like power rakes and vertical mowers, and are thus less likely to cause excess turf injury.

Once done, transfer all the dead matter that you’ve raked off the soil surface to your compost pile. Once the thatch is fully decomposed, it becomes a great source of nutrients for centipede grass.

Note: Dethatching using a hand rake is best reserved for when you have a small lawn and the light thatch buildup. Trying to dethatch an expansive centipede lawn with heavy thatch buildup using a hand leaf rake is tiresome. Power dethatching tools come in handy in bigger fields with heavy thatch buildup.

Use a power rake

A power rake is a more effective alternative to a hand rake. To use a power rake to dethatch your centipede lawn, adjust the vertical tines to a depth of 0.5 inches and space them three inches apart.

Run the power rake in a single direction. Multidirectional passes may cause severe turf injury that may kill your centipede grass. You don’t have to get rid of all the thatch as this increases the amount of stolon injury. The goal is to create as many air and moisture pockets while still preserving the health of your centipede turf.

Note: The spring-loaded tines penetrate the thatch and tear out some of it before dropping the dead vegetation on the surface of the lawn.

Use a vertical lawn mower

You can also use a vertical mower or a verticutter to dethatch centipede grass. The vertical blades pull up the dead vegetation to the surface, thus helping to keep the grass healthy. Attaching a collecting bag to your vertical mower helps. You won’t have to manually collect the thatch you’ve pulled out.

Space the blades three inches apart. The spacing ensures that you don’t cause extensive damage to the stolons, as centipede grass doesn’t have underground runners (rhizomes) and may not be able to recover from excessive vertical mowing.

Note: Immediately irrigate the lawn once you’re done verticutting to keep any exposed roots from drying out.

For warm-season turfgrasses like centipede grass, verticutting is best done in early spring just as the turf is about to green up. You should also fertilize the lawn with a quick-release nitrogen fertilizer one week after vertical mowing for faster turfgrass recovery from physical injury.

Use biological dethatching liquid

Unlike the other dethatching tools, dethatching liquids is a relatively new concept. One advantage they have over aggressive dethatching tools is that they don’t physically damage the centipede grass since they don’t cut through stolons.

Dethatching liquids contain carbonic enzymes and microbes that speed up the decomposition rate of centipede thatch. Most commercial dethatching liquid products are meant to be diluted with water and sprayed onto the lawn. Some of these products contain additional fertilizer ingredients for added value.

Note: You can also make your own dethatching liquid at home using readily available household products like soap.

When is the best time to dethatch centipede grass?

The best time to dethatch centipede grass is when the thatch buildup is 0.5 inches high or more. To determine the height of the thatch, cut out a small triangular section of turf using a shovel and pull it out. Then, measure the depth of the thatch, starting from the base of the grass blades to the top of the soil. If the thatch is higher than 0.5 inches, it’s time to bring out your rake.

Dethatch centipede grass in the spring to allow quicker recovery from physical injury after dethatching. At this time of the year, this warm-season grass grows rapidly during summer. 

See Also: When should you dethatch your lawn?

How often to dethatch centipede grass

The frequency at which you dethatch your centipede lawn should be determined by how fast thatch buildup occurs. As soon as the thatch layer exceeds 0.5 inches high, it’s time to dethatch again. Overwatering or over-fertilization leads to faster thatch buildup on your lawn. You’ll need to dethatch more often if you overwater or overfertilize the lawn. 

How high/low should centipede grass be cut?

You should mow Centipede grass at a height of 1-2 inches. This ensures you don’t get rid of more than 1/3 of the length of the grass blades, thus leaving enough behind blade surface area for photosynthesis.

Centipede grass that’s longer than 2.5 inches is more vulnerable to thatch buildup. Therefore, cut your centipede turf back to 2 inches every time it grows past 2.5 inches.

Note: Use sharp blades when mowing centipede grass. Dull blades yellow the raggedly-cut edges and increase the turf’s vulnerability to disease.

Tips for dethatching grass

  • Mark out sprinkler heads before using a power dethatching tool on your lawn to avoid damaging them and cutting through irrigation lines that are buried close to the surface. 
  • If you’re renting a power dethatcher, ask the owner to adjust the tines or blades such that they cut no more than 0.5 inches into the soil. Also, the tines should be spaced at least 3 inches apart. Ask for a demonstration or an instruction manual if you’re unsure on how to use the machine.
  • Water and fertilize the grass after dethatching to encourage faster recovery from physical injury caused by the dethatching tools.

References

i. Clemson University, Home & Garden Information Center: Centipede Grass Yearly Maintenance Program

ii. University of Georgia- Cooperative Extension: Centipede Grass Decline

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