Plantings that repel insects and, in some cases, snakes, include: holly, marigolds, allium (also known as flowering onion), lemongrass, mother-in-law’s tongue (or snake plant), wormwood (or mugwort), pink agapanthus, flowering garlic, snakeroot, yellow alder, basil, chives, and varieties of cactus. Ants are also repelled by anise, catnip, chrysanthemum, mint, pennyroyal, hot peppers, sage, lemon thyme, rosemary, nasturtiums, and  tansy.