To hem a floor-length dress, measure the target length, mark it, cut the excess fabric, mark and pin the hem, iron it, and use a blind hemming stitch to finish the alteration. Hemming a floor-length dress takes at least an hour minimum and requires the correct thread color, a sewing machine, pins, scissors, a seam ripper, an iron and a fabric pencil.
- Measure the hem
Use the seam ripper to pick out the existing hem, and iron it flat. Try the dress on, and decide on the desired length. Remove the dress, and turn it inside out. Measure the new hem, allowing a half-inch for the hem. Mark it every 2 inches with the fabric pencil. Once the marks are done, connect the dots.
- Cut the fabric
Using the marked line as a guide, cut the excess fabric.
- Pin the hem
Working on the back of the fabric, measure a half-inch up from the bottom of the dress. Use the fabric pencil to mark the new hemline. Fold the fabric up to the line, pinning in place every 2 inches.
- Check the length
Use the iron to press the new hem. Turn the dress right side out, and try it on to check the length and fall of the hem. Make any necessary adjustments.
- Stitch the hem
Set the sewing machine to make a blind stitch. Place the hem of the dress so that the back of the fabric is facing up. Use the machine foot as a guide, and sew along the hem of the dress.