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If you are watchful, you may be able to simply spray cats with a water hose whenever they are trying to use your garden. Cats can be trained, so if you are persistent, this may eventually be enough to permanently drive them away. Be gentle when you are spraying cats with a water hose. Most cats do not like water, so a quick, gentle squirt is usually enough—there is no need for high-powered nozzles, or to thoroughly soak the intruding cats. Motion-activated sprinklers are available from home supply stores. When a cat walks by, the motion triggers the sprinkler, which sprays a burst of water. Most cats do not like getting wet, so this can often be an effective deterrent. Use motion-activated sprinklers to create a border around your garden. These sprinklers can be installed either permanently or temporarily, depending on your preference and needs. These emit a high-frequency sound that cats detest, but which humans cannot hear. These devices are motion-activated, so that when a cat walks by, it is startled by the high-frequency sound and should leave the area. Look for ultrasonic devices at a pet supply store, and use them to create a barrier around your garden. Cats will not linger in areas they do not feel are safe from predators. For this reason, a dog that chases cats can effectively keep them out of your garden.
Spray cats with a hose. Use a motion-activated sprinkler. Use an ultrasonic device to deter cats. Get a dog.