Go to work with the Clone Stamp to build up the flowers. Have them on their own layer using Clone Stamp All Layers. Then duplicate it, blur it, mask parts to remove the blur. Duplicate again, mask other parts... repeat. In this case they probably also did some blurring of a grey, yellow, and brown overlay (colors chosen to match the outfits).
Using this starter image: https://unsplash.com/photos/mqtn_g1ogIY
Quickly masked out the people. But would be much better if you had an overhead photo of people in a field with some flowers.
Added some more flowers using Clone Stamp
Copied them around, very very poorly. Sorry, not my project. You can take your time and do this well though :)
Duplicated it (actually had already duplicated it above) so we can start to blur and mask and blur and mask and blur and mask and you get the idea. Blur different strengths of Radial Blur Zoom by using Smart Object.
Now, I renamed the non-blurred Flowers which rests on top to "Entirely Blurred" and using the mask can remove some of the flowers leaving only the streaks:
Figured now is a good time to put in new grass, mostly because I'm doing this quickly and haphazardly. Ideally, you'll use a photo that doesn't involve needing all new grass.
Blur the field and mask the focal
For composition the Radial Blur is going to work from the center. The people are off-center. Easy enough... group and move the flowers + blurs:
Then just keep adding more flowers and more blurs, here's a few more on the right side.
I'm only using White Flowers but you could bring in more color using different colored flowers and hue adjustments maybe with some Outer Glow as well