Cats love to dig in the gardens. Fences don't keep them out; they simply jump or climb them. Gardeners can spend a lot of time inserting sticks vertically into your soil or scatter fresh citrus peels every two or three days in an attempt to keep cats at bay. An easier and long-lasting way to repel cats is to use one or all of the plants known to be offensive to them.
A herbaceous perennial that becomes woody with age, rue (Ruta graveolens) is known to deter cats. Felines do not care for the smell of it and will not enter a garden if they have to do so by walking between or among rue plants. Fresh or dried rue leaves sprinkled into potted plants may also keep cats away. Rue is hardy in USDA Hardiness Zones 4 through 9 and grows best in full sun.
Scaredy Cat Plant
The scaredy cat plant (Coleus canina) is a half-hardy annual that produces pale blue flowers from July through September. It prefers to grow in full sun and will reach about 18 inches high when grown in fertile soil. Surround your garden with the plants and they will deter cats from entering the garden.
The perennial herb bergamot (Monarda fistulosa L. var. fistulosa) is a member of the Monarda family and the same herb used to make the popular bergamot tea. The volatile oils of bergamot are known to repel both cats and dogs and the plants themselves may do so as well. Bergamot is a herbaceous perennial herb that grows about 2 feet high. The flowers are usually red and are borne in whorls at the end their stems.