I created a similar look by creating simple flower petals. My technique creates a lovely embellishment with a reasonable amount of time and fabric.
To create the petals, make a circle pattern from the kitchen glass of your choice. My circles are 2" in diameter. You could make petals of various sizes for an interesting look. Cut out circles from your fashion fabric without regard to grain line.
Determine where on the garment you want to apply the petals and mark with tailors chalk and a ruler.
Fold a fabric circle in half, then in half again. Cut across the fold removing 1/4" - 1/2" of fabric.
Unfold the quartered fabric circle so it is again a half circle. Pin and stitch the folded fabric circles to your garment varying the spacing. Your petal seams may all point up or down.
The petal seams on the maroon dress alternate direction. Here the top row is placed with the seam pointing down. The next row has the seam pointing up.
It's probably best if the top row has the seam pointing down. Below the first row you can experiment with placement to achieve maximum volume.
Have fun with this easy technique and be creative in the placement of your petals!