To make a homemade cat repellent, chop and mix one small onion with two cloves of garlic and 2 cups of hot water, strain and put the liquid in a spray bottle. Liberally spray the mixture around the desired area, and allow it to dry completely before allowing pets or children access to the area.
Cats are sensitive to many different smells, so cat repellent sprays can be made from a large variety of essential oils, herbs or peels. Cats are sensitive to citruses, lavender, citronella, lemongrass, eucalyptus and peppermint, and homemade sprays can be made by mixing several drops of essential oils with several cups of water. Liberally spray the desired areas and reapply the spray as necessary.
Cats are also sensitive to coffee grounds, citrus peels, pipe tobacco and the herb rue, so these substances can be sprinkled around plants in a garden to deter cats from entering the area and digging up the plants.
Other, non-spray methods for keeping cats away includecovering trash cans, sealing off areas, installing sprinklers or placing rocks or chicken wire on the ground. Cats do not like water, so automatic sprinklers that are connected to motion-sensors will spray the cats, and other animals, as they enter the area, which will deter them from returning. Creating an uncomfortable environment by placing chicken wire or large stones around the area will also deter cats from entering the area.