Homemade weed killers are safe for pets and made by using ingredients from the kitchen. Some ingredients include boiling water, vinegar, salt, sugar and cornmeal. Boiling water kills plants instantly by cooking it while it is in the ground. Vinegar sprayed on weeds also kills them, although particularly robust weeds may require more than one application.
Salt thrown on a patio or brick path offers pet-safe weed control, but should be used with the caveat that it makes the soil uninhabitable for future plants. Sugar also makes soil temporarily inhospitable for plants and kills weeds, unwanted vines and bushes when poured at the base of plants. Cornmeal acts as a pre-emergent for weeds, killing them before they appear.