Hemming Stretch Jeans?

The best thing would be to have a walking foot for your machine, if you have one use it.
If not - do not pull the fabric...if you can - put your finger in back of the feed through and sort of "block" the material from coming through slightly. I saw this on Sandra Bertina's sewing show and it works.
this works by slowing down the botton layer being pulled through, which is why it stretches and which is how the walking foot works..it makes the feed dogs work together pulling the top layer and the bottom layer through at the same time. Without the walking foot the bottom layer is pulled through first, which causes the stretching...this is what you are preventing with your "finger blocking"

I know what to do, I just can not explain it very well, I hope this helps.

Hi: The walking foot is probably your best option. However, if you don't have one, try this:

1. Attach a piece of heavy duty pellon interfacing to the wrong side of the cut edge (by pressing, NOT ironing).

2. Sew with the cut edge down, watching that you don't pull the non-interfaced side, because that will still stretch. Also, having the right side (outside pants leg side) facing UP as you sew, may work a little better because the bottom fabric (feed dogs side) always stretches a little more than the top fabric.

Use the distance between the sewing foot and the bottom edge of the leg as your sewing guide to keep the stitching straight.

3. If you want the edge to look more "store bought" (mass manufactured), fold the hem in on itself until the raw edge meets what will be the final bottom edge of the pant leg & use the "jeans orange" thread that most stores sell. This has the added advantage of not leaving a raw edge on your hem.

Hope this is more helpful than confusing!!