removing moss from lawn

Asked September 26, 2018, 2:20 PM EDT

We are using a shovel to remove moss and have much of it down to the dirt. If we also spray some ultra dawn detergent & water mixture (2 oz to one gallon of water) to kill the remaining moss, how long to do we have to wait to re-seed that area? Any other ideas to remove moss and replant grass this fall? Thank you!

Hennepin County Minnesota

1 Response

The use of detergent to control moss has been known for a long time. The detergent acts as a surfactant with respect to such plants as moss. Exactly why a detergent such as Dawn, has a negative impact upon moss and other plants, including grass, is still rather speculative. It is known that surfactants will increase the ability for substances, such as the detergent, to enter the moss plant itself. Current thinking is that once the detergent has entered moss, it has a detrimental effect upon the membranes of moss cells. In moss, this is evident by a browning of the plant, However, it is important to stress that these effects may or may not extend to the roots of the moss. Consequently after applying the detergent and removal of the brown moss, it can still return from roots that remained in the ground.

Grass can also be impacted by detergent. For this reason, it will be critical that you minimize the amount of detergent that lands on grass. Using a sprayer with a highly-focused stream will be important. Once the moss has turned brown, vigorously rake the area to remove as much of the browned moss as possible. Water well both the specific area and the surrounding grass. This should remove much of the residual detergent. Then add an inch or so of top soil and reseed.\

The following sites will provide more information on this procedure:

http://www3.extension.umn.edu/local/article/moss-your-lawn

https://homeguides.sfgate.com/kill-lawn-moss-dish-soap-41529.html

https://www.thespruce.com/dish-soap-as-moss-killer-3969992

https://www.hunker.com/13406267/how-to-apply-dawn-to-kill-moss

One final point. If you remove the moss at this time and then reseed, much of the grass seed may not germinate until the spring at which time all traces of the detergent should be gone.

Good Luck!!