How to Hem a Layered Gown OnlineFabricStore Maker's Mill How to shorten a dress without hemming from the bottom Naomi Fata Easy way to hem a prom dress. Its easier than cutting first. You sew first. , mark the hem. Subtract 1 2 for hem. , mark with chalk marker and turn to the inside on chalk marks. I hemmed 2 Cut Out Satin Mermaid Hem Prom Dress Parthea Fashion Strapless Polka Dot Cut Out Long Prom Dress with Bows Black White 00