Before you start your plan of using vinegar as an overall weed killer, consider that it will kill more than just the weeds. However, when used properly, vinegar makes a natural spray that will kill weeds. If you prefer, choose an organic vinegar. It may cost a bit more, but you can be sure that the weed killer is completely without synthetic chemicals. Vinegar, generally, contains 5 percent acetic acid. This ingredient draws all the moisture out of any type of vegetation, killing it. This is why you should never use it on a windy day or directly near other plants, without first protecting them.
Combine 4 cups vinegar, ¼ cup salt and 2 tsp. liquid soap in a spray bottle. There are many similar formulas, with varying amounts of ingredients. In fact, you can use straight vinegar. Salt works in the same manner as vinegar, drawing moisture from the plant. Soap helps the vinegar and salt stick to the plant. It also breaks down the surface plant wax, allowing the other ingredients to enter more readily.
Cover all plants in the near vicinity with a plastic tarp before spraying. Spray the vinegar weed killer in cracks of sidewalks or driveways. Gravel walkways are another safe place to use this mixture.
Reapply the spray a few days or weeks later, if you spot regrowth. The root systems of some mature weeds may survive the first application.