Her first album, The Water Lily, was released in 1977, on the Philo label. In 1980, her second album, Forgotten Dreams, consisting mainly of covers of songs by contemporary North American songwriters, was released on the Flying Fish label. In 1982, Herdman left Philadelphia and moved to the small rural community of Pine Plains, New York, where she met her husband, Dick Hermans. In 1983 she then released her third album, Seasons of Change. To date, Herdman has released 12 albums, including several in a trio with Anne Hills and Cindy Mangsen.