Mattress stitch is worked with the right-side up and becomes invisible from the right side when finished. Mattress Stitch Seam on Stocking Stitch Step 1 With the right sides facing you, lay the pieces to be sewn flat with edges next to each other, lining up rows and stripes as much as possible. Insert the needle between the first and second stitches on the first row. Slide the needle under two rows, then bring it back to the front between the first and second stitch of the row. Step 2 Return to the opposite side and, working under two rows throughout, repeat this zig-zag process, always taking the needle under the strands that correspond exactly to the other side and going into the hole that the last stitch on that side came of,being careful not to miss any rows. The secret to the Mattress Stitch is to keep the seam elastic without allowing it to stretch too much. The best way to do this is to work very loosely for a few inches, and then pull the sewing yarn so that the stitches pull together. Give the seam a little tug from the top and bottom to add a bit of stretch back in. If purl rows are on the right side, you may have an easier time working under one row rather than two. Mattress Stitch Seam on Garter Stitch When joining garter stitch, work into the center of the first stitch of the row instead of between the first and second stitches. When the seam is pulled closed, the garter stitch ridges will line up correctly. Watch our how-to video to learn how to make an invisible seam using the mattress stitch. This video shows how to work the mattress seam on a stocking stitch by working through the center of the edge stitch—another option for vertical seams. Plus, get garter stitch seam tips. Mattress Stitch Seam on Ribbing When joining two ribbed sections, work into the center of the first stitch of the row instead of between the first and second stitches. When the seam is pulled closed, one complete knit stitch will be formed and the seam will be nearly invisible. Mattress Stitch Seam When Working with Bulky Yarn When seaming knits made with thicker yarns, such as super-bulky Bernat Blanket yarn, you may use a thinner yarn in a similar color as your work to join the pieces. That will prevent the seam from getting too bulky. Watch our how-to video above/below for tips.