By Jennifer Vanasco The floral designer known as Mr. Flower Fantastic wears a gas mask and gloves because he's allergic to flowers. New York Botanical Garden hide caption Mr. Flower Fantastic has worked with some big names and brands: Serena Williams, Michael Jordan, Spike Lee, Nike, Louis Vuitton, Netflix. Recently, when the Chicago Bulls retired point guard Derrick Rose's jersey number, Mr. Flower Fantastic covered an outdoor basketball court in a portrait made of roses and carnations. "It took thousands of flowers to pull this off — in the middle of winter. In Chicago," the artist said, laughing. "It was really special." Hundreds of people lined up in the cold to see it. A post shared by Flower Fantastic (@mrflowerfantastic) The floral artist — who says he often goes by "MFF" or "Flower" — stays anonymous because he wants the focus to be on his work. Usually when he's out in public, he wears a gas mask and gloves, which both hide his identity and protect his health (ironically, he's allergic to flowers).…