I wanted to add a garter stitch border to help with rolling. I added 4 extra stitches when I cast on (2 on either side) and each row now goes as follows:

RS: k3, ssk, k9, yo, (k1, yo, k10, md, k10, yo) repeat brackets until 15 sts remain, k1, yo, k9, k2tog, k3
WS: K4, p to last 4 sts, K4

I knit each stripe for 18 rows.