Harth was engaged to work alongside Peter Zimmerman Architects to construct a large headhouse and commercial greenhouse on Stoneleigh, the public garden of Natural Lands, on the historic Haas Estate in Villanova, PA. Given the prominence of the original mansion and carriage house, the new structures needed to be historically compatible and complementary while fulfilling the functional demands of a modern horticultural operation.
A key challenge was the technical integration of the greenhouse and headhouse assemblies, particularly achieving a durable, weather-tight connection between two very different building systems. A JANCO greenhouse system was utilized, built slab-on-grade with linear floor drains the length of the building and two double door vestibules providing generous exterior access. The stone-clad headhouse, with arched windows, brick accent banding, and a matching yet higher vaulted roof line, sits harmoniously adjacent to the greenhouse. The headhouse offers ample work area along with a vestibule with covered entry, office, and ADA-compliant restroom. Additional storage is provided in the headhouse’s partial basement which includes exterior stair access. For aesthetic continuity, the headhouse’s dark mica quarry cut stone veneer is continued on the foundation walls of the greenhouse and capped with flagstone. Natural materials, including copper gutters and downspouts, were carefully selected for the buildings to exemplify the beauty of the surrounding gardens.
Harth’s close coordination with the executive leadership at both Stoneleigh, A Natural Garden, and the Natural Lands Trust ensured that the facility was not only architecturally appropriate, but also optimized for daily planting, propagation, and seasonal workflows. The result is a highly functional, mission-aligned facility that enables the Executive Director and horticulture team to increase seedling production and sales by a factor of five, directly supporting Stoneleigh’s educational programming and long-term sustainability – a true success! Harth is honored to have partnered in this project.
Architect: Peter Zimmerman Architects
