Coffee grounds can be an effective way to deter squirrels from your garden or home. When sprinkled around the edge of a garden, coffee grounds can help to create an unpleasant smell which squirrels will want to avoid. Additionally, as squirrels are repelled by the acidic scent, they are likely to stay away from any areas that contain coffee grounds. To maximize effectiveness, spread the grounds regularly and make sure to replace them after rain or heavy wind.