Which seaming method for a hood?

I knitted the hood part of my pattern in a strip, and now I have to sew the cast-on edge together. (The hood is in garter stitch where the cast-on edge is.) I’m clueless about which stitch to seam with. I do want it to look as invisible as possible, but stitches like Mattress Stitch only work for the sides of the knitting. :shrug:
In case it helps, the pattern is here: http://www.craftbits.com/project/knitted-silver-cape under “To complete”.

Thanks for any help!

The directions are to fold the hood doubled and join the cast on edge to form the back seam of the hood. But the cast on edge and the cast off edge are basically equivalent, each are rows of garter st. So, you could switch them and for a neat and fairly invisible seam, you could take out the [I]cast off[/I] that you’ve just finished, fold the hood and do a 3 needle bind off on the live sts to join the cast off edge. That will be the back seam and the cast on edge will frame your face.
If you’d like directions for the 3 needle bind off (and it’s a great technique), go to the Free Videos tab at the top of this page, Tips, Seams, 3needle bind off.

I was actually planning not to cast off until I’m sure that I like the size, and I wanted to get the most accurate fit without casting off by sewing the seam first. I don’t know what to do now… Also, I’m knitting the straight rows on circular needles, so it wouldn’t really be problematic if I seamed the edge first, while the stitches are still live.

Not hard to do this. Put one half the sts on any other needle, smaller is fine, and use the unoccupied end of the circular needle to do the bind off. That’s the needle that determines st size anyway. Hold the right sides of the hood facing each other so the seam will be on the inside.

I think you misread what I said. I know how easy three-needle bind off is, but that wasn’t my point.

Russian grafting may be what you’re looking for.