Why is My Cat Eating Grass? Have you ever wondered why it is that your cat is eating grass? Off the bat, as long as there is no pesticides or fertilizers on the grass, eating most varieties grass is safe, and even good for cats. Some people even plant them a patch in the yard, or in a pot for indoors. In my experience one of the benefits to having healthy, quality grass in my yard is that the cats love to eat it.