There are two versions of this cast on, both worth learning!
It's also a fantastic way to cast on non-provisionally! Just use working yarn instead of waste yarn for a cast on that is nearly identical to your bind off. This makes it excellent for symmetrical items like cowls.
Version 1: Crochet Chain Cast On
This is the more basic version, where the knitter crochets a chain and then picks up loops from the chain to create stitches.
Using waste yarn, make a crochet chain:
Step 0. Start with a slip knot on your crochet hook.
Step 1. Wrap the yarn clockwise around the hook (the opposite direction to a regular yarn over);
Step 2. Catch the yarn in the hook;
Step 3. Draw the yarn downwards through the loop on the hook to create a new loop.
Do steps 1-3 as many times as you need stitches to cast on, plus a few extra stitches (2 - 5) to make room for potential mistakes. Once you have reached the last stitch, break or cut your yarn and draw the end through your final loop.
Then, using your working yarn:
Step 1. Insert your needle tip into the first bump on the back of the chain, closest to the initial slip knot;
Step 2. Draw your working yarn through, knitting the bump.
Repeat these steps until you have the number of stitches on the needle that you need for your cast on. This is where the extras come in handy: if any bump is hard to pick up or looks wrong, skip it.
Treat this row as your 0 row; no shaping or patterning should happen on this row, for your own sanity.
Version 2: Crochet Over Needle Cast On
This version of the crocheted provisional cast on can be daunting to ponder or learn - what with the knitting needle and the crochet hook both sitting in your hands like porcupine quills. However, once you get the knack of it, it's a wonderful way to provisionally cast on - easy to do and equally easy to remove.
You’ll use one knitting needle, a crochet hook, and waste yarn.
Begin by making a slip-knot on the crochet hook.
You will now use the crochet hook to make loops over the tip of the knitting needle as follows. Hold the knitting needle in your left hand and the crochet hook in your right hand.
- Put the knitting needle (in your left hand) behind the crochet hook (in your right hand). Put the working yarn (attached to the slip knot on the crochet hook) under and behind the needle.
- Bring the working yarn up and around to the front of the needle so you can grab it with the hook.
- With hook, draw a loop of yarn through the stitch already on the crochet hook. One stitch will have been formed on the knitting needle and you'll still have one on the hook.
- Put the working yarn straight back down below and behind the needle.
Repeat until you have cast on to the knitting needle the desired number of stitches.
For a provisional cast on using waste yarn only: work a few extra crochet chains not onto the knitting needle. Carefully pull on this chain to unravel the provisional cast on and pick up live stitches when the time comes. From their work as directed in your pattern.
Here's a video by Lucy Neatby about removing your provisional cast on.