Suggest, when you sew the hems use short length, narrow width zigzag stitch. Let the machine feed the material while you guide it. Don't hold back on the material, just steer it. Take it slow, it's much quicker than hand sewing. Finally pre-stretch the bolt ropes for a couple of days by hanging them from the ceiling with a weight on the bottom. There is a stitch on most machines that sends one stitch wider than the rest which if used with a special foot will guide material and rope and can be set to pick up the rope every few stitches. Because they both go through the machine together they both pick up the same stretch. Takes a bit of practice though. Love the colour.
Jerry.