Cats have a strong reaction to smells because their sense of smell is 14 times that of a person’s. Their receptors extend throughout their whole head. So they use this superpower to avoid danger, to sense smells and mates.
Cats hate the smell of citruses such as lemon, limes, oranges, and grapefruits for a good reason. Cats like to put as much distance between themselves and citrus fruits as possible. Lemon, in particular, is toxic to them if digested. Uses this citrus at your garden to keep them away.
Like citrus oil, hot peppers contain capsaicin, which cats instinctively avoid because it’s toxic to them. Cats detest the smell of spicy foods and plants like mustard.
Cayenne pepper sends cats running because it acts as a repellent. But this can be harmful and cruel to cats.
Cats also hate herbal scents like lavender, rue, geranium, absinthe and lemon thyme are especially unpleasant to them. Cats also dislike eucalyptus oil and oil of wintergreen.
Keep in mind, that cats are individuals. Some will tolerate unpleasant smells better than others and some will disregard otherwise repellent smells entirely. If one course of action doesn’t work, try another, you’re likely to find a scent that works well at keeping cats away from where you don’t want them to be.