Since 1829. One of the largest and most prestigious indoor flower shows in the world. Held by the Horticultural Society in the City of Philadelphia for the promotion of this interesting and highly influential branch of Science. The fledging PHS boasted 80 members in 1827 but today the membership is ocer 23,000. The first Flower Show was held at the Masonic Hall on Chestnut Street, where the well-known Christmas favorite, the poinsettia, was introduced. Over the decades, the event has grown dramatically to become the nation's grandest Flower Show, attracting nearly 300,000 visitors annually.