Gathering fabric is a great way to create volume in a dress. For great gathering effect, it is better to use your sewing machine. Hand-stitching the pleats would just result to frustration and wasted time, especially if the fabric that you want to gather is very wide.

For a flowy dress bottom, cut a rectangular fabric. The part that you’ll gather [and attach to the bodice] should be more than the total width + 1″ but less than twice the total width.

Sew this part. Cut the thread without fastening it. Pull the bobbin thread. This will make your fabric gather nicely. Stop pulling when you reach the exact width for your dress. Attach to bodice by sewing over the same sewing line.