The Woman's Board of the Chicago Horticultural Society established the Library in 1951. In 1959 it contained 584 volumes. With the opening of the Chicago Botanic Garden and its Education Center in 1976, the Library's growing collection of 6,000 books moved to a new facility to better meet the needs of its users.
Today, the collections of the Lenhardt Library hold approximately 125,000 volumes including books, periodicals, rare books, special collections, videos, DVDs, slides, nursery catalogs, and the archives of the Chicago Horticultural Society.
The Lenhardt Library strives to provide plant science resources and accurate information to users by collecting, organizing, preserving, and sharing subject-specific materials for current and future use, while supporting all objectives of the Chicago Botanic Garden.