Learn to Crochet - Seams
Various methods can be used to join pieces of crochet and, again, the use of the finished item often dictates the assembly method. Sewn seams can be invisible or decorative. Below are a few suggestions for joining pieces of crochet.
(1) To join with an invisible sewn seam, place pieces edge to edge with the wrong sides facing up and whipstitch together.
(2) To join invisibly using a crochet hook, place right sides of pieces together and slip stitch through one loop of each piece as illustrated.