White vinegar is an effective weed killer. The acetic acid in vinegar kills weeds, and although any vinegar will work, vinegar with a high acidity level is the most potent.
Since vinegar is a nonselective herbicide that kills weeds and garden plants alike, it is best to apply vinegar using a spray bottle that lets the liquid land directly on the weed. Vinegar can be sprayed on weeds in early spring before they spread. It's also good practice to spray dandelions and other perennial weeds in the early fall. When vinegar is applied, it is absorbed through the weed's leaves and directed to its roots before it penetrates the weed's core and kills the weed.