The Garter Tab Cast On is how I start all of my top down shawls; I love this cast on! I didn't love it at first though. In fact, I didn't like it and stayed away from it. Why? Because it seemed hard and confusing, and I really didn't understand what in the world it was for.
This way of thinking is of course, silly. Nothing is hard once you learn to do it. In order to learn, you must do. And it's just yarn - if you don't get it the first time (and you probably won't), try again and again until you get it.
One day I tried it and discovered it was sooo easy and I love it! There really isn't anything hard about it. You cast on a few stitches, pick up and knit a few more stitches, and there you have a garter tab cast on.
The main reason I wanted to master the garter tab cast on is because I really wanted to knit a top down shawl. I couldn't quite wrap my mind around how you could knit a triangle shawl starting from the top, instead of from the bottom point. I wanted to know! The only way I knew to start a top down shawl was with the garter tab cast on. I know now it isn't necessary to use a garter tab, but it is my preferred method. And by the way, top down shawls aren't hard to knit either. They are just as easy to knit as a bottom up triangle shawl.
Before we begin, I will say that this is only one way to do a garter tab cast on. Some knitters prefer to do a provisional cast on, and then when ready to pick up along the cast on edge, remove the waste yarn and pick up the live stitches. Too much muss, fuss, and fiddle for me. This tab is such a small part of the knitting, nobody is even going to notice. If you'd like to see the provisional cast on method, just do a search and you will get plenty of results.
For the garter tab cast on, I normally start with four stitches, because I have this thing about even numbers, but often you will see patterns call for you to start with three stitches and knit six rows. In addition to my 'thing' for even numbers, I think four is just easier to work with than three. So for our purposes here, we will use four.
Cast on four stitches.
Knit eight rows.
After last row, do not turn work over. Instead, keeping the same side of the work facing you, turn the tab 90 degrees clockwise so that the left side of the tab is now facing up - you will pick up and knit four stitches along the side.
Now, turn the tab again so that the cast on edge is facing up; you will pick up and knit four more stitches along the cast on edge.
You should have a total of twelve stitches and are ready to begin.
This is just an example; always cast on/knit/pick up the number of stitches your pattern directs. Even if you are working with a different number, the method is the same.
Once you have the required number of stitches on your needles, continue on with your pattern. I usually knit a plain row before beginning the increases - that is just how I do it. You can do whatever you feel works best for you.
Since this technique is/can be confusing in writing, of course I have a video to show you how it is done.
Here you go, and Happy Knitting!