Provisional Cast-Ons: The Crochet Chain Cast-On

This is my current fave provisional cast-on. It combines ease with relative quickness (nothing is faster than Elizabeth Zimmermann's yarn-around-the-needle approach, but it is more complicated to work off of down the road). All you need for this method is a crochet hook of about the same size as your needle and some waste yarn of approximately the same size as the working yarn--but if it's thicker even that is not really a problem.
Begin by making a crochet chain that has a few more chains than the number of stitches you need to cast on. FYI, this is some leftover handspun from my Zora cardigan. Not sure why I'm wasting it on this, but it was sitting in my leftover basket so here it is.

When you have enough chains, cut the waste yarn, end the chain off, and tie a knot in the cut end, like this.

 

This isn't strictly necessary, but it helps to identify the end of the chain where you will begin the unravelling process later on when it's time to work in the opposite direction.

Now, have a look at your chain. On the front side, you have something that resembles a braid (see above), but on the back side notice what looks like a series of purl bumps.

With the working yarn and needle, and starting at the end nearest the knot, begin to knit up stitches into those bumps, like this.

 

After a while, this is what will emerge. See how the braided front side of the chain runs along the bottom of your stitches? Keep in mind that these stitches count as your cast-on, not as the first row of knitting.

When it's time to undo the provisional cast-on and work in the opposite direction, simply untie the knot and unravel the first crochet stitch. For the rest, the chain can be simply "unzipped", leaving live stitches in its wake. Or, if you are nervous about losing any of those precious stitches, work into them before pulling the crochet loop out, in the same manner as shown here. So easy!