Green Acres

In the early 20th century, when a rural Pennsylvania arboretum found itself destined for the lumber mill, business mogul Pierre Samuel du Pont stepped in to purchase the property and save the historic trees. In the decades since, he and his philanthropic successors have continued to add to its grounds, creating Longwood Gardens: 1,100 acres of meadows, woodlands, fountains, and conservatories displaying all manner of rare and exotic plants. That legacy of preservation now underpins the institution’s latest chapter, a 17-acre transformation designed by the architecture firm Weiss/Manfredi in collaboration with landscape studio Reed Hilderbrand. At the heart of the project, debuting November 22, is a new 32,000-square-foot conservatory, overlooking the Brandywine Valley and seemingly immersed in a reflecting pool. Unlike existing masonry buildings, the asymmetrically pleated edifice will provide…