Vinegar is a proven and effective weed killer. Mixing salt with the vinegar can help to permanently remove weeds from common trouble spots, such as crevices in sidewalks or driveways.
Vinegar is a non-selective herbicide, like most commercial products that kill weeds. This means that it can kill desirable plants like flowers. Vinegar, however, poses no risk to people, animals or the environment, unlike many commercial products. Five percent vinegar is strong enough to kill weeds, although it may take more than one application to kill stubborn weeds.
The major issue vinegar has is that it has no residual action to prevent new weeds from popping up in the future. While permanent removal may not be important in many circumstances, it may be desirable in others. Using a mixture of one cup of salt inside a gallon of vinegar can help permanently kill weeds in gravel paths or on concrete walkways or driveways. Adding a tablespoon of liquid dish washing soap to the mixture will help it to better stick to weeds when applied.
The weed killer can be funneled into a plastic spray bottle for easy application. It should be used on a dry, sunny day. Coating all surfaces of the weed in this solution will kill it in a few days. After use, the mixture can be stored in a cool, dark place until it is needed again.