The quarry operation ended in the early 1900s, and English ivy and undergrowth took over. The Mimosa Garden Club sought to turn the former quarry into a quiet oasis for contemplation and a site for studying plants native to Georgia. With the financial assistance of the Price Gilbert Jr. Charitable Fund, the garden club obtained professional advice for landscaping and plant selection, and the dream soon became a reality. The garden was dedicated in 1976 to the memory of Mary Howard Gilbert, one of Mimosa's founding members. Today this garden showcases plants native to pre-settlement Georgia in a natural, granite enclosure.
Paths lead past shaded woodlands, granite outcrops, a pond, a stream, and a waterfall.
Highlights include trillium, ferns, and magnolias. In the mid-1970s, the Azalea Chapter of the American Rhododendron Society, led by late nurseryman Frank A. Smith, began constructing a new garden to illustrate two of Atlanta's most beautiful plants. Coinciding with the 1975 completion of McElreath Hall, volunteers cleared away weeds and other undergrowth, purchased rhododendrons, and graciously donated their own azaleas. The Rhododendron Garden's contemporary design respects the land's existing terrain and furnishes ideas for shade landscapes. The idea for an Asian-American garden was conceived by Center horticulturists in 1988 as a way to compare the evolution of Asian plants with those of the southeastern United States, two areas with many climactic similarities.