Homemade Weed Killer: Mix: 1 quart vinegar (can use white or apple cider vinegar), 1/4 cup salt, & 2 tsp. dish soap. The acid in the vinegar kills the plant. The salt pulls moisture out of the weeds. The dish soap keeps the weed killer on the plant. Word to the wise: this mixture will kill any plant it comes into contact with; it's not selective at all. Once you mix up your weed killer, pour in a spray bottle. Then, wait for a day that is going to be dry, hot and sunny and spray away.