If you have plants on the floor, consider relocating them. Some of them may be toxic to cats. Also, depending on where you got your cat, it can defecate in different places because your cat might not know what the litter is. So your plants will look like a perfect place for your cat to have their need done. You don't have to throw your plants forever; you can move them for a small period until your cat learns how to use the kitty litter.