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The horizontal mattress stitch is a popular way to join two stockinette knitted pieces together.

The mattress stitch comes in handy when you need to join cast-on and bind-off edges of your knitting project. This stitch resembles a row of knit stitches and creates an “invisible seamless look”. The result is really smooth and clean.

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HORIZONTAL MATTRESS STITCH | STEP-BY-STEP TUTORIAL

To seam the edges together it is best to use the long cast on yarn tail, that way you will have fewer ends to weave in, and fewer knots.

The tail should be at least three times longer than the edge that you are going to seam (plus you will need to add extra length for the weaving in tail). If the tail isn’t long enough just use a matching yarn.

For demonstration purposes, I am using a contrasting color.

STEP 1: With the right sides facing you, place your knitted pieces parallel to each other and line up the edges. You will have a top piece and a bottom piece. You will be working from right to left.

STEP 2 (bottom piece): Locate the first stitch, that is directly under the bind-off edge. Insert your tapestry needle through the center of that first stitch (from back to front, through the center “V”), and pull the yarn through.

STEP 3 (top piece): Locate the first corresponding stitch, that is directly above the cast-on. Insert the needle underneath that stitch (under both legs of the V), and pull the yarn through.

STEP 4 (bottom piece): Insert the needle through the center of the first stitch again (from front to back), and bring it up through the center of the next stitch (from back to front).

STEP 5 (top piece): Insert the needle underneath the corresponding stitch, and pull the yarn through.

Continue in this manner: work into the center of the stitch on the bottom piece, and under the stitch on the top piece. You will see a row of knit stitches forming.

Don’t tighten the seam too tight as you work, you want the height of the seam to match the height of your average knit stitch.

I hope you found this horizontal mattress stitch tutorial useful! Be sure to check out other knitting tutorials!