Step 1

Undo the last purl stitch worked and place the unworked stitch on the LH needle. (1 stitch left unworked from the previous round) Cut yarn, leaving a very long tail, approximately 5 times the length of the total width of the stitches to be cast off. Thread the tail through a darning needle.

Step 2

Insert the darning needle knitwise into the first stitch and drop that stitch.

Step 3

Insert the darning needle purlwise into the next stitch and pull on the yarn, DO NOT pull all the way through; leave a loop towards the end.

Step 4

Insert the darning needle into the loop from front to back and pull through. First reduce the size of the loop, then pull on the yarn tail to tighten.

Repeat Steps 2 to 4 until 1 stitch remaining on LH needle.

Next Step

Insert the darning needle knitwise into the next stitch and drop that stitch. Locate the next stitch that is hidden under the cast-off edge and on top of the purl column, insert the darning needle purlwise into that stitch, pull on the yarn and leave a loop.

Next Step

As Step 4.

Thread the yarn to the wrong side and weave in the end.

You can find Valerie's videotutorial here.