Vertical stripes also means that you have to chain the length, and each row adds to the width.
I had no idea how long to chain, so I chained about 255 stitches. It's hard to keep track exactly, but it's about that long. That was probably too long, but it's okay.
I chained with pink, then did a row of double-stitch of pink, red, orange, yellow, green, blue, and purple. It didn't look quite symmetrical or even, so I finished the purple with a row of slip-stitch to try to imitate the chain on the other side.
It looked really good, and then it started curling. That's probably because I don't always use even tension in my stitches. It makes big curlicues out of the whole scarf, which is fine, but then it starts folding in half on itself. It ends up looking like I'm wearing a yellow disc around my neck. You can see it sort of try to begin doing that in the pictures.
Love and Rainbows,