From Neighborhood Cats:
The Coleus Canina plant, a weed originating in Europe, is known as the "Scardy-Cat" or "Pee-off" plant because it emits an odor offensive to cats (but not to humans) and deters their presence. Recommendation is to plant them three feet apart around the area to be protected. You may need to order cuttings or seeds from a nursery or dealer. Do a Google search for the plant to find a dealer and compare prices - one dealer when last checked is Rosy Dawn Gardens. WARNING: There are many varieties of Coleus plants, so make sure you order the correct one - Coleus Canina. Order early in the spring planting season before dealers run out of stock.
For protecting gardens or flower beds, common household items may be effective, including the herb rue, either planted or sprinkled in its dry form. Other suggestions for garden areas are orange and lemon peels (cats dislike citrus smells), cayenne pepper, coffee grounds, pipe tobacco, lavender oil, lemon grass oil, citronella oil, peppermint oil, eucalyptus oil, and mustard oil.
Havahart Dog & Cat Repellents use capsaicin, pepper and oil of mustard as its active ingredients. It repels by both taste and odor, has a lemon scent, lasts 7-10 days and needs to be reapplied after rain or new growth.
