I agree, press seam open. That should help. I cut a bias strip approx. 1&1/2", press a little less than half. Stitch the inside curve down, flip open and trim the bottom piece back to about 1/8". Now turn under top piece and stitch. If the stem is too fat, trim a little off before turning under. This way you can make stems any width you would like. This probably doesn't make much sense but perhaps you can find a tut on you tube that will explain it better.