Squirrels are not the cute, wonderful creatures found in Disney movies. Because wild animals can cause damage as well as carry diseases, you do not want them on your patio. To keep the squirrels away in a humane fashion that will not harm them, employ different methods that have been found useful for others looking to have a squirrel-free patio. All you need are supplies from a hardware store or home and garden center; no specialized equipment is necessary.
Pour ground cayenne pepper into a salt shaker. Sprinkle the pepper on the edges of the patio, including the back wall leading to the house. Continue to sprinkle the pepper until there is a discernible line of pepper visible. Replenish this line of pepper on a regular basis or after a rainstorm or other act of nature that washes the pepper away.
Plug a pest-control ultrasound module into an AC outlet on the outside wall of the house. If the AC outlet is too far away from the patio, extend the range of the module using an extension cord so that the module can be placed on the floor against the back wall of the patio. The ultrasound will drive the squirrels away from the patio.
Spray a deer repellent on the ground around the perimeter of the patio. Spray the edges of the back wall and any rain pipes or other extrusions that a squirrel could climb on. Spray the underside of the furniture on the patio with the repellent. Replenish the repellent on a regular basis to repel the squirrels from the patio.