Overseeding and Dealing with Thatch in Lawn
Q. During late fall I put down some centipedegrass sod. Will it harm my centipede sod if I overseed my new lawn with ryegrass seed?
A. The ryegrass can compete with the permanent grass. I have seen centipede lawns that were weakened during spring green up, attempting to outcompete the ryegrass. The extra fertilizer also can cause problems for centipedegrass, possibly inducing centipedegrass decline.
In general, there are pros and cons for overseeding. The reason that most people overseed is because they want a green lawn during winter. Personally, I’m ready to put the mower away for winter and I take a break and my lawn takes a break. But this is personal preference. You’ll have to make that decision. There is definitely the possibility of causing some damage in your centipedegrass as a result of overseeding. More information on overseeding is available through the below UF/IFAS Extension website.
Q. There is a lot of thatch in my St. Augustinegrass lawn. Can I burn this thatch out?
A. Many times, what people are calling thatch is really not thatch – it’s just dead grass blades on the soil surface. True thatch cannot easily be removed. It is a layer of dead and living plant debris (mainly dead grass stems, runners and roots). It is a layer that builds up over time under the grass and above the soil. It forms a layer that looks somewhat like peat moss. Dead leaf blades do not contribute to this thatch layer. They simply breakdown too fast. A brisk raking will remove the dead grass blades that are intermingled in the grass. Sometimes it’s surprising how much you can rake out. In order to remove thatch, you have to use a vertical mower (dethatcher). Or, some people will topdress the lawn to help more quickly breakdown the thatch. If the thatch layer becomes too thick, it can cause some problems in a lawn. Fertilizing too much, watering too much and sometimes overusing fungicides are the main reasons why thatch becomes a problem. Basically, you’re growing the grass faster than the microorganisms can breakdown the debris. If it’s just grass leaves and not true thatch, I don’t know that I’d worry about it too much. If you do use a vertical mower in St. Augustinegrass, only go in one direction and not in a checkerboard pattern. As far as burning the lawn, many municipalities do not allow burning and there is always the gamble of the fire getting out of control and the heat can injure the lawn. More information on thatch is available at the below UF/IFAS Extension website.
Larry Williams, UF/IFAS Extension Office, Okaloosa County, January 11, 2017