Lay the rug flat on a hard surface. Measure the edges you will be applying the fringe to. Add 1 inch to each of these measurements. Cut one piece of fringe to these measurements for each side of the rug.
Fold both short, raw edges of one piece of fringe under ½ inch and pin in place. Lay the fringe on top of its corresponding rug edge and adjust it so the finished top edge of the fringe overlaps the rug ½ inch. Straighten the fringe so it runs evenly along the edge and pin into place. The folded edges of the trim should just meet each outer edge of the side of the rug. Repeat with each side of the rug that will be getting fringe.
Thread your sewing machine with heavy-duty upholstery thread in a color that coordinates with the fringe. Change the sewing needle to a heavy-duty size 18 or upholstery-weight needle.
Sew one section of the rug. Sew along the top finished edge of the fringe, through the fringe and the rug, using a ¼-inch seam allowance. Because this is a heavy-duty project, take your time sewing to allow the sewing machine to feed all the layers of the fabric through. Backstitch when you start and stop your seam.
Sew this section again, this time using a ½-inch seam allowance. The double layer of stitching will solidly secure the fringe to the rug. Remove the pins from this section and repeat with all other sections that have fringe pinned to them.
Remove all the pins. Lay the rug flat on the floor and comb the fringe to ensure it is straight and even. Trim any uneven fringe with a sharp pair of scissors.