From Glastheim (P), head south 2 maps and west 1 map. You should be on Far isld03. On that map, make your way to the lower right portion and you should find Denny (Located at 222, 107)
After speaking with him, he will tell you to go look for a giant red flower.
Head east 1 map, and north 1 map, to Far isld04. Locate the flower around 362, 44.
Next head back to Denny, who will send you to find a master botanist in Glastheim (P)
Warp back to Glastheim (P) and on the west side, speak to Henrith located around 86, 236.
Now, go to where the Flower was located and after speaking to it, will give you 2 Red Petals.
After obtaining 2 Red Petals, head back to Denny and he'll thank you as well as take away 1 of them.
Finally, return to Henrith and he'll let you trade the last Red Petals that you have, as well as some other items listed below, for a Chung Hairband