Edge your granny square in a different colour to the last round. To edge your square, work one double crochet, back loop only, in each stitch around the edge of the square. Beginning at one corner ...

Free Loop: This is the front loop you did not crochet in the previous row ... Row 4: Hdc in 19 stitches, 1 dc in back loop only of next stitch, hdc in next 20 stitches. Change colors.