The blanket stitch is a stitch used to reinforce the edge of thick materials. Depending on circumstances, it may also be called a whip stitch or a crochet stitch. It is defined as A decorative stitch used to finish an unhemmed blanket. The stitch can be seen on both sides of the blanket..hen done by machine, it may be called a whip stitch or, sometimes, a Merrow Crochet Stitch, after the first sewing machine that was used to sew a blanket stitch. This machine was produced and patented by the Merrow Machine Company in 1877.