A large variety of flowers; the sight of many flowers blooming together. Figuratively, a profusion of beautiful things.
春の庭園は百花が咲き乱れていた。
The spring garden was filled with flowers blooming everywhere.
詩人は旅先で見た百花を歌に詠んだ。
The poet composed a poem about the many flowers he saw on his trip.
この公園は季節ごとに百花が楽しめることで有名だ。
This park is famous for the variety of flowers you can enjoy each season.