Liquid Soap to Kill Weeds on the Lawn

Liquid Soap

• You can mix five tablespoons of any liquid soap, such as dishwashing soap, in one quart of water. Store the mixture in a spray bottle. Spray on weeds, being sure to thoroughly coat them with the soap mixture. This method works best on hot days, according to the website Healthy Child Healthy World.

Soap and Vodka Formula

• Another recipe with liquid soap calls for a few drops of liquid soap, one ounce of vodka and two cups of water. Place in a spray bottle and shake well. Spray on the leaves, coating them until the liquid runs off. This method only works in the sun. Alcohol breaks down the leaves' protective waxy coating, which causes them to dehydrate in the sun.

How Soap Kills Weeds

• Soap kills weeds two ways. First, soap breaks down the waxy surface on many weeds. This also breaks the water's surface tension, meaning that the mixture sticks to the leaves longer. This longer exposure increases the effectiveness of the killing agent. Second, soap is derived from oil, which kills plants. As a bonus, the soap makes it easier to see which areas have been treated so that the weed is thoroughly coated.

As a Pre-emerge

• Prevent weeds before they have a chance to grow by sprinkling corn meal gluten around plants and on your lawn. It will prevent weeds from sprouting. The corn meal gluten won't kill plants that are already growing, nor will it kill weeds that have already sprouted.