Patio furniture cushions are often exposed to harsh weather conditions that can degrade the fabric of the cushion. The most common failures of patio cushions are seams that open and cuts that happen when a cushion encounters a sharp object and is punctured or torn. Both of these problems can be repaired fairly quickly and cheaply, allowing you to get more use out of your cushions before you need to replace them.
Clean the patio cushion, using a vacuum cleaner and upholstery shampoo to remove all dirt and grime.
Repair a simple cut or tear where the edges of the torn fabric fit well together by mending the cut. Use heavy-duty buttonhole thread and a curved upholstery needle. Cut 36 inches of thread and thread the needle, pulling the two threads even. Tie a knot 1 inch from the end of the threads that is large enough that it will not pull through the weave of the fabric.
Paint the edges of the cut with no-fray liquid. No-fray is a type of arresting clear fabric paint that will prevent the edges from fraying. Allow one hour for the no-fray to dry.
Slide the curve of the needle inside the cut and 1/4 inch beyond the end of the cut. Bring the needle up from the inside and through to the outside, and pull the threads snug. Stitch across the cut, using a crossover stitch. Pierce the fabric 1/8 inch from the edge of the cut. Take the curved needle under the cut and bring it up across the cut from where the stitch started. Pull the thread until it is snug. Pierce the fabric 1/8 inch from where you started the last stitch, and come up 1/8 inch from the second piercing of the first stitch. The stitches should be 1/8-inch apart and even in length as you go across the cut.
Finish by going past the other end of the cut and sending the needle through the stitches at least 1 inch. Trim the end of the threads.
Cut an iron-on patch 1-inch larger on all sides than the hole itself for a larger hole. Insert the iron-on patch through the cut with the adhesive side up. Bring the cut together as much as possible. Place scrap cotton over the patch and iron until the patch is firmly attached.
Hand-sew seams together if the cushion does not have a zipper back. Tuck the seams under to their former positions and use a small crossover stitch to bring the fabrics together.