Double Garter stitch:

Row 1 (RS): Knit.

Row 2 (WS): Knit.

Row 3: Purl.

Row 4: Purl.

About Double Garter Stitch: This stitch pattern creates deep horizontal ridges, more prominent than standard garter stitch. It's handsome worked as a hem, and looks good as a dividing line between other stitch patterns.