Adopt environmentally safe methods to kill unwanted grass, especially if you have children or pets who spend a lot of playtime outside. These methods leave no residue in the soil and are easier on the wallet. In fact, most of these products probably are present in your kitchen cabinet or will require a visit to your local supermarket instead of nursery or garden supply center.
Pour boiling water directly over grass for a simple, inexpensive and environmentally safe method. Use this method to kill large patches of grass or small areas between bricks or driveways. Pour a stream of boiling water from a tea kettle to kill unwanted grass in walkways or driveway cracks. The water burns and dries the grass, killing it immediately. Wear closed-toe shoes and long pants to prevent splashes when pouring boiling water.
Household white vinegar is a safe and effective way of killing grass. Vinegar contains acetic acid that burns grass. Use vinegar that contains 7 percent or more of acetic acid, which will kill the grass on the first application. Pour it directly over grass for large infestations or spray it for targeted plants. The sun acts as a catalyst that speeds the grass-drying and killing process. Use vinegar during hot summers and turn off sprinklers before application.
Black Plastic or Newspapers
Another environmentally safe way of killing unwanted grass is to smother it. Mow the grass and spread heavyweight black plastic. As an alternative to plastic, place eight to 10 sheets of newspapers over the area. Spread an even layer of mulch over the plastic or newspaper to hold it in place and push the grass closer to the ground. Grass needs oxygen, sunlight and water to live. Plastic and newspapers block those essential elements. Plastic also acts as an oven, retaining heat and cooking the grass to a quicker death.