Common Cat Repellants
Cats are notorious for showing up where they are not invited. How often have you visited a cat-owned home and seen the resident cat ignore the visiting cat-lovers and plant himself squarely in the lap of the only cat-hater in the room? Cats seem to enjoy a challenge - especially if that challenge is a garden. But sometimes, you don't want cats getting into certain areas, sometimes for their own good, sometimes for your own sanity.
Cats Vs Gardeners
Perhaps you have something new and tasty in your garden, such as a nest of rare breeding birds. Or, perhaps you are quarantining a new cat in your garage and want to keep any feral cats from him or her? Unfortunately, cats can't be bribed. It would be great to go up to all of the neighborhood strays with open cans of premium cat food and tell them "There's more for you if you just stay out of my back yard." Fortunately, there are lots of commercial and homemade cat repellant choices for you that will not harm the cats.
You can plant blooming roses in parts of your garden. Apparently, most cats do not like the smell of roses. You can also leave lemon peel or spray lemon juice or lemon essential oil around the garden. Cats do not like the smell of lemon. If you have any plants in acidic soil, spray vinegar around. Cats also find vinegar to be a strong cat deterrent. Cayenne pepper is also used and recommended by many gardeners, but a lot of feral cats learn how to doge the pepper after a couple of weeks.
One of the best homemade cat repellants is really awful perfume. The kind of perfume that you can smell a mile away is perfect as a cat deterrent. Usually, the perfume is not harmful for plants, but you might want to make do a patch test on grass to see how it handles the perfume. The stinky perfume is also good for keeping cats off window ledges, buildings, sheds, and patio furniture. The only problem is you'll have to get used to the stinky perfume.
Many gardeners recommend putting out moth balls as a cat repellant, but this can kill the cats, as sometimes cats eat the moth balls. You really can't risk a lawsuit by accidentally killing a neighbor's beloved pet. Also, passing dogs or curious babies may also eat the moth balls. Skip the moth balls.
Another recommended homemade cat repellent is to squirt a hose at the cat whenever they come by or squat. You just want to shock the cat, not knock the cat over. Well, I hope you would not want to knock the cat over. Some people think a water gun works better than a hose. A fire hose is right out, no matter how many plants the trespassing cats have eaten.
There are many commercial cat repellants (or "cat deterrents") available in garden stores, pet shops and online. Read the directions carefully, and be sure to wear gloves for chemical sprays. There are some non-chemical repellants that emit an ultrasonic electric pulse that many cats can find annoying. Many rodents can find this annoying, too, so be sure you don't have any rare rodent species or pet rodents like guinea pigs, hamsters or gerbils that you want to keep in your garden in order to use this kind of cat repellant.
When all else fails, get a cat-chasing dog. Then, all you'll have to worry about is the dog wrecking your garden, but at least a dog can be happy using only one spot of your garden as a toilet, instead of the whole garden. Then remind yourself at how gardening is supposed to make you appreciate nature's inherent powers rather than your lack of powers.
Keeping a Cat Off the Furniture
This is far more difficult, as a cat thinks the entire universe was made for his or her comfort, let alone your couch. If you can leave a few drops of stinky perfume or lemon juice on the furniture, this can work. However, be sure the stinky materials won't harm your furniture.
Another cat repellant is tin foil. Cats generally don't like the feel or crinkly sound it makes. Leave a long sheet tucked in over the cushions of a couch, for example.
All else fails, just move the furniture to a room where the door is closed all of the time and, when you are sure Kitty is not in the room, shut the door. This will cause much less stress in your home than trying to watch like a hawk over a favored chair or sofa over every move the cat makes. In the end, what's more important to you - a living companion or an inanimate piece of furniture?