You've finished knitting all the pieces of a cardigan sweater -- two fronts, two sleeves and a back. You followed the pattern, checked the gauge and the pieces are perfect. You can't wait wear it. However, before you impress all your friends with your handiwork, you have to sew the pieces together. Many knitters find this last stage a chore -- it's not knitting but sewing. If you don't rush the process and use the pattern as a guide, the sweater will go together easily.
Wash and block the sweater pieces. Use the pattern instructions and a tape measure to block each piece to the dimensions provided in the pattern schematic. Also follow the washing recommendations of the yarn. Let the pieces dry completely before continuing.
Sew the shoulder seams together, matching the two front pieces to the back. These seams should be sturdy, so hold right sides together and use a back stitch.
Add a collar along the neck edge or button bands along the front edges, if your pattern calls for it. It is easier to complete these items before you add the sleeves and while you can hold the pieces flat. Don't forget to add buttonholes on one button band.
Sew the sleeves into the armhole. Start at the centre of the sleeve cap and work to outer edge, matching the ends. Add ease if needed. Work the seams with the right sides facing up, and sew with a weaving or mattress stitch, which is invisible when completed.
Sew up the side seams, using the same weaving or mattress stitch, matching the underarm seam and the bottom edge and the sleeve cuff.
Sew on buttons if needed. Wash and dry the assembled sweater.
Use the same yarn you knit the sweater with to assemble the pieces. The curved pieces of the sleeve cap are often the hardest to join. You may find it helpful to pin these pieces together before sewing.