Straight or diluted vinegar can be sprayed around the edges of a garden, and on plants, fences, posts and garden decor to keep cats away. Concentrate the spray on areas that the cats frequent or that you particularly want to protect. Vinegar can be sprayed safely around the base of acid-loving plants, but should be tested for safety before being sprayed directly on leaves. Some plants will not be affected by vinegar; others might turn brown. Also, test an inconspicuous spot for fading or damage before spraying vinegar on painted surfaces or garden decor. Spray every few days or as often as needed to repel cats. Areas likely will need to be sprayed again after rain or watering.