Casting on in crochet is pretty straightforward. If you already know how to make a slip knot, you’re all set. The basic idea is to make a slip knot in the working yarn and place the slip knot onto the hook. The slip knot is perfect for this application because it can be tightened and loosened as needed. For those who don’t know how to make a slip knot (I had to learn it too!), I’ll provide a tutorial here. There are many ways to make a slip knot and they all follow the same idea of pulling a loop through a loop. This tutorial follows the method I learned.
Next, you will bring the working yarn under your fingers, up across the front of your fingers, then cross it over the tail and release it to hang down the backs of your fingers again. This makes a complete loop around your fingers. I typically use the three longest fingers as shown in the picture below.
Now it’s time to grab your crochet hook (or you can use the fingers of your other hand). Slip the crochet hook under the loop around your fingers (on the non-palm side of the hand), grab hold of the working yarn that is dangling back there and pull the working yarn through the loop toward you. You have pulled “a loop through a loop”.
The piece of working yarn that was just pulled through the loop on your fingers is the loop of the slip knot that will stay on your hook.
Keeping the loop on your hook, remove your fingers from the loop they are in. Pull on the tail to gently snug closed the knot. It shouldn’t be tight.
Then, pull on the working yarn gently to snug it up loosely to your hook. All finished!
Crochet patterns will never tell you to make a slip knot to get started. They assume that you know to do this. Whether you are crocheting a flat piece (back and forth like a dishcloth) or crocheting in the round (making a seamless tube or circle), you will always begin with slip knot. Even a magic ring cast on is built off of a slip knot.