Mattress stitch is a very easy way to join pieces of knitting together. It is worked with the Right Side of the work facing you, so is especially useful if you need to match a pattern, or stripes.
For a neat finish, pin your pieces of work together. If you are joining a seam on a large piece, such as a sleeve, you may like to pin it in several places. I am using a small stocking stitch sample here to demonstrate.
Mattress stitch is worked from right to left. Thread your sewing needle with yarn. I am using a contrasting colour here, but you would typically use the same colour yarn as your knitting.
Insert your sewing needle into one piece of knitting and pull the yarn through leaving a short tail.
Insert the needle in and out of one stitch on the other piece of knitting.
Repeat this, working alternately into each piece, until you have worked approximately 6 stitches – any more than that and you risk your yarn tangling.
Hold the short tail end of yarn, and pull the long length to close the seam.
Repeat this along the length of your seam, working 6 stitches at a time, to the end of the seam. Remove the pins as you reach them.
When complete, the seam is almost invisible.
Sew in your loose ends.
That’s how to work mattress stitch!