The sixth solar term-Grain Rain falls on April 20th. Moutan Peonies, also known as tree peonies,usually bloom near Grain Rain, so they are also called "Grain Rain Flower". The custom of appreciating tree peonies in Grain Rain has been going on for thousands of years.

The tree peony, with its large and fragrant flowers, is known as the "king of flowers" and "national beauty and heavenly fragrance". Its colorful flowers and graceful posture symbolize noble and elegant spiritual qualities.

The cultivation of treepeoniesin Sichuan began in the Tang Dynasty and was widely cultivated by the Song Dynasty. The poet Lu You once wrote "Tianpeng Peony Book", saying, "In Central China, the tree peony in Luoyang is the best. In Sichuan, the tree peony in Tianpeng is the best." Peony cultivation in Sichuan is mainly located in Chengdu City, Pengzhou City (ancient name of Tianpeng) and Mount Emei. Especially, the tree peony flowers in Pengzhou are the most prosperous ones. Danjing Mountain in Pengzhou City is the best place to enjoy tree peonies in Sichuan.