Hemming a patagonia merino shirt

Mark the end you want for the sleeve – mark it all the way around. Make a second line at least one inch beyond the first. Fold or roll the excess under (inside the sleeve) and pin it. The sleeve end marked line should now be at the end of the sleeve. You can finish it by hand wit a whip stitch, or by machine with a straight stitch. Especially with the second option, try to keep the stitching line near the inside edge of the hem.

I have now showed you the, *ahem* , Hemming Way! (Groan!)

I would do a simple rolled hem so there is no exposed cut surface – see http://www.backwoodsdaydreamer.com/diy-guides/sewing-skills/

Most modern zigzag sewing machines have special stretchy sitches for hemming wool and other stretch jersey materials. If you have a manual it should have a few suggestions. I recently converted a merino long sleeve into a tshirt and the fancy stitch worked great. My Bernina manual recommends a basic zigzag for jersey material, but there are many other stitches that will do a fine job. That being said, a straight stitch is fine as well.
Matt