Most of the material, filed by corporate or individual name, consists of invoices and receipts from nurseries in the United States and Europe. Folder titles include business locations noted in brackets. Almost all invoices are itemized, detailing the types of flowers, plants, shrubs and trees used to landscape the various residences. Two landscape contractors particularly well documented include F.D. Moore & Sons and Upper Bank Nurseries. The former serviced Parkgate and Bernice Wintersteen's home at Chestnut Hil, and the latter worked primarily at Rittenhouse Square. Many folders also include correspondence, notes and catalogs. The folder of blueprint drawings designed by landscape architects Wheelright & Stevenson pertains to Parkgate. In regard to Glenveagh, McIlhenny's correspondence with James Russell in the "Sunningdale Nurseries" files offers significant documentation of the plantings and garden designs there. McIlhenny also consulted with noted garden designer and journalist Lanning Roper on seasonal plantings at Glenveagh. Although only a few of Roper's invoices exist in this subseries, some of his letters with McIlhenny in the "Correspondence" series highlight his expertise.
In addition to documenting the plantings and maintenance of the various gardens and grounds held by the family, McIlhenny's passion for flowers and for sharing his horticultural expertise with others also becomes evident. While stationed in Virginia, the young lieutenant patronized a few local florists, sending holiday corsages for several women in New York, Columbus and Norfolk. In other years to his overseas acquaintances, such as the Countess Bismark of Italy and the Marchioness of Londonderry, McIlhenny occasionally sent plantings of sweet corn, watermelon and cucumbers, buying from seed and gardening firms across the country. For almost thirty years, McIlhenny ordered regularly and frequently from several Philadelphia florists, spending as much as $500 some months to decorate his home. Some invoices make note of which flowers would adorn a particular room, while other invoices refer to grander arrangements no doubt for McIlhenny's dinner parties. Even the Savoy Steak Shoppe served as an outlet for fresh cut flowers. In remembering friends and family, McIlhenny preferred to say it with flowers as well, sending numerous arrangements through local florists, such as Pennock.
Most of the files identified by subject pertain to specific flower and plant types. The "Greenhouse" files pertain to the construction and later renovation of such a structure at Parkgate. Philadelphia architect Carl A. Ziegler oversaw the work, which in 1938 cost $3,800.