It is actually the boiling water that destroys the protective wax coating of the grass allowing the salt to be absorbed. Boiling water and heavy salt mixture. There are also organic weed killers available.

Hi, you may want to try using rock salt like that used for melting ice off your driveway. It's been many years since I used it to help kill off some overgrowth of sweet peas in a neighbor's yard. We put it on fairly heavy and then simply watered the area with a sprinkler for about an hour. Those sweet peas took about 4 years to start growing back. Good Luck! Jim D./Heathsville, VA