Lace edge of shrug

I can’t find a pattern to do what I want, so I’m making it up. I want a shrug out of feather and fan lace with mohair yarn. My question is, when I cast on, my stitches are much tighter than when I knit the lace pattern. How do I get the cast on (and probably bind-off) to be as loose as the lace? Do I use larger needles just for that row? It’s supposed to be a pretty scalloped edge according to Barbara Walker.

You most definatley can use a larger needle to do the cast on row and if you don’t want to switch needles you can hold two needles together when doing the cast on row and then pull the second needle out before you start knitting the second row.

It is hard to cast on loosley!!!

I found a loose cast on method, and it leaves a chained edge similar to the BO edge. You purl the single stitch, then put it on the needle the way you would a knit cast on which twists it a bit. It’s not very fast, but I find that it’s much looser than any of the others, but has a firm edge.