Use this technique to cast on temporary stitches with scrap yarn - when you knit into these stitches with your real yarn, the first row will be held on the scrap yarn chain for later. When you unravel the provisional row, the first row will become live stitches, so you can work in the other direction, or graft ends together seamlessly, etc.

Many leethal patterns use this cast on; most include this tutorial within the pattern for easy access.

Here is a video of it in action:

A video posted by Lee Meredith (@leethalknits) on Jan 14, 2016 at 8:48pm PST

provisional cast on stitches with a crochet hook and scrap yarn

Use a scrap yarn the approximate weight of your project yarn, something which will unravel easily later - cotton works well.

start with a slip knot, tightened onto crochet hook; hold hook to side of needle, with yarn running underneath needle

grab yarn with hook from over needle

pull loop of yarn through slip knot (first stitch)

bring yarn from front of needle back to underneath it

repeat crochet stitch, pulling yarn over needle through loop on hook; continue repeating steps for as many stitches as you need

make a crochet chain of several stitches - this chain will tell you where to start unraveling when working with the provisional stitches later

After casting on, work first row with normal working yarn, beginning knitting into the end where the cast-on ended (with the chain).

To use the live stitches later, unravel the chain from the stitches one stitch at a time, slipping live stitches onto knitting needle. Pull out crochet chain from 1 stitch, slip it onto needle, and repeat for each stitch, carefully so nothing unravels.

Note: when you transfer the provisional stitches onto a needle later, there will be one fewer stitch than the original cast-on number.