One of the things about knitting stockinette stitch is that it does tend to curl around the edges which doesn't really make for a nice finished product. But there are ways around it. One of those ways is to knit on a border. I'm going to show you how to knit a really cool garter stitch border around a stockinette piece which would be great for say, a scarf.
We have stockinette in the center with garter stitch around the edges. To begin you would just knit garter stitch for your bottom border as long as you want it to be. As you knit you decide how many stitches you want your border to be, in this I've chosen five and five, and however wide you want your stockinette portion to be. In this example I've chosen fifteen.
I am working a slip stitch edge. I'm going to slip the first stitch as if to purl and put the yarn behind. Then I'm going to work the front side of garter stitch which is to knit across five. Then I'm going to start my stockinette portion which on the front side is also to knit. If it's confusing to you, especially in the first couple rows feel free to put a stitch marker between your border portion and the body of your stockinette piece. That just helps you when you come to the beginning of the stockinette to realize that you're leaving the border and entering the stockinette.
I've just finished the stockinette portion and here I am at the final five stitches for the garter stitch border which I'll work in knit. For this I'm working in knit across the entire piece, the front of the garter stitch, the front of the stockinette, and the front of the garter stitch. On the back however, you'll remember that garter stitch is on the back is knitting and stockinette stitch on the back is purling.
So here's where the switch happens. I'm going to slip my first stitch as if to knit and put the yarn behind. I'm going to knit across the front with my border five stitches. Now I'm at the stockinette portion which means I have to purl on the back. I've moved my yarn to the back for the purl stitches. It's important that you move your yarn in between knits and purls otherwise you'll get an accidental yarn over and you'll make a hole.
I'm purling across my stockinette portion which in this sample is fifteen stitches wide. When I get to the final five stitches, one, two, three, four, five there they are, I'm going to move the yarn because this is garter stitch and garter stitch means that you have to knit on both the front and the back. Now I have finished the back and you can examine the fabric that we're making. Garter stitch on both sides with stockinette in the middle. This prevents the stockinette from curling.
Here is my knitted stockinette scarf with a border of garter stitch. When you get to the end of your piece don't forget to repeat this part. That would be garter stitch across the front and the back, no more purling.
There are of course, other borders that you can use to keep stockinette from curling. One is a knitted on I-cord which you can do in a different color to sort of offset your stockinette portion. Or you can do a knitted on I-cord in the same color as your stockinette portion and that makes a really tidy rolled edge.
Those are some ways to knit a border onto your knitting.