This method works in plain garter stitch as well as lace patterns that do not have purl rows. The example shown is the Gentille cowl. This does not work in stockinette stitch. Look at how the edge looks finished:
HOW TO DO IT
The trick is simple: slip the first stitch of every row purl-wise with your yarn in front. Then move your yarn to the back and continue knitting!
Now you know! Use this tip from anything like scarves to blankets!