The Sunken Garden is the oldest garden on the grounds, originally designed by Theodore Klein and resembling several he built for local customers.
It was rehabilitated between 2002 and 2005 through the efforts of volunteers from the Oldham County Master Gardeners and Green Thumbs Garden Club.
This garden contains plants that are designed to give the feel of an alpine environment, even though it includes plants from such widely spread climates as the Himalayan Mountains, deserts of southwestern North America, and Central America.
In order to give these plants a fighting chance in a Kentucky climate, most of the soil in the garden was removed and replaced with granite grit, coarse sand and pea gravel to provide excellent drainage, which is especially essential for the cold-hardy succulents from the Southwest.
The Sunken Garden is maintained by a group of volunteers who have worked on the garden since its rehabilitation.