You can join crochet seams by using a tapestry needle or a crochet hook, using one of these four methods
1 Sewing with a tapestry needle is the regular and neat way to join seams. Place two pieces of crochet right sides together and oversew them as shown above, using a tapestry or yarn needle.
2 To slip stitch a seam, place the crochet pieces right sides together. *Insert hook into both edge stitches, yrh and pull through to complete 1 slip stitch; rep from * working into the next edge stitches, keeping work fairly loose.
3 For a dc seam, place the crochet pieces right sides together, or wrong sides together for a visible seam. Work as for slip stitch seam, using double crochet instead of slip stitch.
4 A useful variation on the dc seam, the dc and chain seam is used when less bulk and/or greater flexibility is needed. Work 1 double crochet and 1 chain alternately.