Cats spray to mark their territory. The small amount of urine in cat spray has a pungent smell that's especially obnoxious in warm weather. So what should you do if stray cats mark your home as part of their territory? The best way to get cats to stop spraying is to get them spayed or neutered, which also keeps the cats from yowling all night and prevents unwanted kittens. If you can't capture the cat and take it to an animal shelter for neutering, try these other ways to keep stray cats away from your house and garden.
Find where the cats are spraying, and spread a few pinecones around the area. Prickly pinecones like ponderosa are the most effective. If the cats are spraying in your garden, lay down some course bark around the area. Cats prefer soft places to walk around and dig, so the pinecones and bark will make it an uncomfortable place for them.
Fill some ribbed water bottles with water and set them around the area where the cats spray. The motion of the light refracting in the water makes cats nervous, which may keep them from spraying there.
Fill a spray bottle with a 50/50 solution of white or cider vinegar and water, and spray around the places the cats have been. Cats don't like the smell of vinegar and it should deter them. Of course, the vinegar doesn't smell great either, but it's probably better than cat urine.
Sprinkle coffee grounds or the ground-up peels from citrus fruits in the places where the cats spray. Coffee and citrus are also smells that bother cats.
Sprinkle red pepper flakes in the sprayed areas. The hot oil from the pepper flakes is a strong deterrent for all animals.
If the inexpensive methods above fail, for about £58 (average 2009 price), you can buy motion activated sprinklers. Cats hate getting wet, so a few squirts of cold water will encourage them to spray elsewhere.
If you sprinkle or spray any material to keep cats away, be sure to replace the material every few days, particularly after a rainstorm. If you try the motion activated sprinkler, be sure to move it around regularly so the cats don't learn to avoid the sprinkler and spray in other parts of your house or garden.
Steps 1 through 3 are cheap, natural, and harmless ways to discourage cats from spraying on your property. Try these methods first, because steps 4 and 5 use materials that may harm the cats, children or other animals.