The Garden occupies the more than 30 acres that originally served as the farm and nursery for the Idaho State Penitentiary. The Old Penitentiary shut its doors in 1973, and for 12 years the land lay dormant. Dr. Chris Davidson and the first board of directors negotiated a lease in 1984 and transformed the area from rock, weeds, and rubble into beautifully cultivated gardens.

Today the Idaho Botanical Garden has blossomed into numerous specialty gardens, each with a unique focus. Included are a contemporary English Garden, a Meditation Garden, a Children's Garden, and an Heirloom Rose Garden, among others. New in 2006 is the Lewis and Clark Native Plant Garden. This garden offers visitors the opportunity to "experience the journey," as they move through 4 different habitats and their representative plants as described by Meriwether Lewis in his journals. A demonstration garden will display the many potential uses of native plants in modern western landscapes.