Today I want to share my favorite method for hemming knits - using the blind stitch hem. This method is neat and sturdy and works for pretty much all knits except very stretchy lycra jerseys. I have hemmed everything from rib knits to thick sweater knits with good results. To get the best result you do need a serger, but it can work without if the knit is stable (like double knits and sweatshirt knits). Serging the edge keeps the fabric from growing, which is especially important when you are working with thin rib knits and interlock fabrics.
First serge the edge with a flatlook seam. Make sure that the tension is high, you don't want the knit to grow. If you don't have a serger, just leave the hem raw.
Fold the hem over and press again.
Set up your sewing machine for blind stitch hemming. The thread should match the fabric. Sew the seam making sure the seam is even and that it catches the fabric (but not too much). Also don't stretch the fabric when sewing, as this will distort the hem.