Some stitch patterns in knitting are known to create finished works that curl along the edges. This effect is typically unwanted and is often frustrating, especially to novice knitters. The cause of curling can usually be attributed to the stockinette stitch or other stitch patterns based around stockinette. You can avoid curling by substituting the stockinette stitch for other patterns that lie flat, working your stitches to add flat edges or by sewing a lining onto the back of your project.
Use a stitch other than stockinette stitch when knitting. The stockinette stitch, which is made by alternating rows of knitting and purling, almost always curls around the edges. Substitute this stitch for other stitch patterns. The garter stitch is made by knitting every row. The seed stitch, moss stitch and ribbing patterns are made by alternating between knitting and purling within each row. Check a pattern dictionary to find other appealing substitutes for stockinette that will not curl.
Add a different stitch pattern to the edges of your stockinette project. If you do not wish to substitute a non-curling stitch for your entire project, you can work a few rows on the top and bottom of your project, as well as a few stitches on each edge. Work four or more rows of garter stitch, seed stitch, moss stitch or ribbing when you begin and end your project. Work four or more stitches in a garter, seed or moss stitch pattern at the beginning and end of each row. This will keep the edges from curling under and allow your piece to lie flat.
Sew a lining onto the back of your project. If you have already knitted an entire piece only to find that it curls, or if you must knit something entirely in stockinette, a fabric lining will add structure to your knitting. Cut a piece of fabric to match your project's size and hem the edges if necessary. Sew it onto the wrong side of your work using a sewing needle and thread. The firm weave of the attached fabric will anchor your project in place, eliminating any curls.