Vertically knit bands are knitted in the same direction as the sweater body, from bottom to top. A vertical band allows you to knit a ribbed band that matches the bottom ribbed edge of your sweater.
Border bands keep the center edge of a knit piece from stretching. Bands also add a neat trim to an otherwise rough-looking edge and create a place for fastenings — usually buttons.
Knitted-in vertical bands: Vertical cardigan bands knitted in at the same time as the sweater are convenient and easy. No need for further finishing — you just knit to the end of the row for your front panel and continue to knit the stitches for the band. Their drawback is their lack of stability.
Worked on the same size needle as the sweater body, the bands don’t always make a taut edge.
Vertical bands knitted separately: You can work vertical bands as separate pieces and later join them to the front of the cardigan. You just cast on the number of stitches you need to achieve the width of your band and then knit it up — be prepared for a lot of turning! Generally, you make the band on a smaller needle than the sweater body to give it more stability. Sew the band to the sweater edge using the mattress stitch.
If you find your knitted-in vertical band less than successful, try to work the band in a stitch pattern with a shorter row gauge, such as a garter stitch band on a stockinette stitch body. You can also work the band on separate double-pointed needles in a smaller size. Just work the band on the smaller short needle, and then work the body on the larger needles.