mattress stitch is the name of what you are looking for.
It's a squared off zig zag- if you were sewing a seam from bottom to top you would go straight up- straight over- straight up on the other side- straight over... nibbling your way up one row of stitches at a time.
If you ever find a direction to "graft" stitches then you would need the kitchner stitch- that works the live knit loops at the top edge rather than the row edges.