The Historic Gardens Postcard Collection includes 200 postcards of historic views of various public gardens, parks, monuments, and buildings throughout the United States and some foreign countries, including Canada, France and Cuba. Some private gardens and estates and many Washington, D.C. attractions are also represented. Roughly half of the postcards were mailed; the remaining postcards were not written on or posted. Areas represented include Arizona, California, Colorado, Delaware, Florida, Illinois, Indiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Nebraska, New Jersey, New York, Ohio, Oregon, Pennsylvania, Texas and Virginia. Foreign views show gardens in Havana, Paris, and Canada. About a dozen cards feature various views of Smithsonian Institution museums along the National Mall in Washington, D.C.

The Ken Druse Garden Photography Collection contains approximately 45,000 film transparency and 35mm slide images, dating from 1978 to 2005, of gardens, garden features, and flora photographed by garden writer and photographer Ken Druse. The photographic images document numerous private and public gardens throughout the United States and a few in Canada. Many have appeared in Druse's own books and articles as well as those by other writers. Approximately half of the collection is arranged according to specific garden, the other half by garden feature. A small portion of the collection consists of slide lectures given by Druse. Some images are identified with general captions and dates. Images documenting specific gardens are sometimes accompanied by handwritten notes, garden descriptions, and articles. Annotations appearing on certain images indicate the publication in which they appeared. The collection includes 'outtakes' or bracketed images that give insight into Druse's photo shooting process.

Collection consists of 183 35mm photographic slides that Dr. John M. Fogg took of a variety of arboreta, botanic gardens, plant nurseries, and other assorted gardens throughout the United States and Canada between 1955 and 1967.

The William Lyman Phillips Collection includes thirty glass negatives and two glass autochromes showing a sampling of gardens presumably designed by landscape architect William Lyman Phillips. The gardens are located in Massachusetts, Florida and unidentified locations.

The Perry H. Wheeler Collection includes the design, client and business records of Perry H. Wheeler, a landscape architect best known for his work on numerous townhouse gardens in the Georgetown neighborhood of Washington, D.C., during the 1960s as well as the redesign of the White House Rose Garden in collaboration with Rachel Lambert ('Bunny') Mellon during the Kennedy administration.

The J. Horace McFarland Collection includes over 3,100 photographic images of private and public gardens throughout the United States, as well as some from foreign countries, dating from 1899 to 1963. Many of these images, generated for Mount Pleasant Press (later the J. Horace McFarland Company), were used to illustrate trade catalogs published by the firm as well as journal and newspaper articles. The collection also contains color records that were used as reference aids during the printing process, plant patents, and various publications of the McFarland Company.

The Corliss Knapp Engle slide collection contains 35mm slides of gardens, garden features, flower shows, and flora photographed by Corliss Engle, a self-taught photographer and horticulturalist. Much of the collection is comprised of photographic documentation of numerous private and public gardens that she visited throughout the United States. Of particular note are images of Engle's own garden in Brookline, Massachusetts, spanning three decades; they provide excellent insight into the development and evolution of a garden over time. Portions of the collection highlight Engle's involvement with the Garden Club of America and the GCA's Garden History and Design Committee. The collection also includes various notes, lecture scripts, brochures, programs and articles on garden and plant-related themes generated or compiled by Corliss Knapp Engle.

The Historic Gardens Stereograph Collection includes 807 stereographs that depict various public gardens, parks, and tourist attractions throughout the United States, with an emphasis on features related to horticulture and landscape design, including plants, garden furniture, and topiaries. Most, but not all views, show exterior features. A number of stereographs indicate the photography studio on the recto or verso, as well as a series or image number. Many include a brief caption; some include a lengthy description on the verso. Few are dated.

This collection contains over 37,000 35mm slides, 3,000 glass lantern slides and garden files that may include descriptive information, photocopied articles (from journals, newspapers, or books), planting lists, correspondence, brochures, landscape plans and drawings. Garden files were compiled by Garden Club of America (GCA) members for most of the gardens included in the collection. Some gardens have been photographed over the course of several decades; others only have images from a single point in time. In addition to images of American gardens, there are glass lantern slides of the New York Flower Show (1941-1951) and trips that GCA members took to other countries, including Mexico (1937), Italy, Spain, Japan (1935), France (1936), England (1929), and Scotland. A number of the slides are copies of historic images from outside repositories including horticultural and historical societies or from horticultural books and publications. The GCA made a concerted effort in the mid-1980s to acquire these images in order to increase its documentation of American garden history. Because of copyright considerations, use of these particular images may be restricted.