If you want to keep cats away from your vegetable garden or prevent them from marking your front door as their territory, one solution is to make your own natural cat repellant. Such a solution is easy to make, safe, economical and can prove very effective.
In a medium bowl, gently mix lemongrass scented dish washing soap and castor oil, then add 1 cup water. Use a natural-formula dish washing soap made with vegetable oil instead of petroleum oil. You can purchase castor oil at most health food stores or pharmacies.
Carefully pour your homemade cat repellant mixture into the clean spray bottle. If you can use a recycled spray bottle, all the better. If you don't have a spray bottle, you can soak old sponges in the cat repellant solution, then wipe or drip onto foliage, or affected areas.
Spray your natural cat repellant around the perimeter or your home or yard that the cats frequent. Reapply your homemade cat repellant periodically, especially after rain or if the area has been irrigated by sprinklers.