This particular cardigan is blue and yellow, but since I didn't have a suitable navy cardigan, I went with plum. And the great thing about this tutorial is that the process can be used for any other embellished item you might want to copy.
Start with a basic crew-neck cardigan and some yellow scrap fabric:
Next, pull up your picture of the cardigan on your computer. Zoom in on the separate designs and print. (The design will end up very fuzzy and pixelated, but you can get a good general idea of the shape you want.) Cut out these shapes, and you have a pattern for your yellow flowers.
Pin the shapes onto the yellow fabric and cut. Using your picture as a guide, pin the pieces into place and stitch onto the cardigan. (I would do this one at a time- I kept poking myself with stray pins as I was sewing. Kind of annoying.)
I wore it with the yellow skirt that I recently dyed and, in true Emma Pillsbury fashion, a ruffly button-down. (SO glad I left the top of the skirt white. The yellows on the cardigan and the skirt match perfectly!)