The Valley House Sculpture Garden, originally designed by the renowned landscape architect Clarence Roy early in his career, is sited on 4.5 wooded acres in far North Dallas. The Garden won a major design award in 1960 for the best garden design for its size category. For a number of years, the gallery hosted spring exhibitions of many notable sculptors including Charles Umlauf, Sorrel Etrog, David Cargill and a one-person show of Henry Moore in 1969. From 1980 to 2005, Erika Fakac, chief designer at Lambert's, married into the family and further enhanced the garden through developing consistent plant palettes, bulb and perennial displays. A hidden treasure in the metropolitan Dallas-Fort Worth area, the garden continues to host sculpture shows, private receptions for the art community, and is open to the public six days a week.

Since 2005, Tary Arterburn has acted as curator of the garden, advising the Owners on horticultural management and designing two additions to the garden near the gallery that add outdoor space for receptions and sculpture exhibits.