A resilient green landmark in the heart of Manhattan

From soil-based planters to a futureproof system

The original living wall, installed in 2016, consisted of soil-filled planter boxes mounted on a steel framework. While visually impressive, long-term performance proved challenging in this exposed urban environment. There was a need for a more robust and reliable solution. To futureproof the façade without compromising its visual identity, the focus shifted to durability, plant vitality and maintenance efficiency.

Sempergreen was invited to deliver a system capable of meeting these demands while preserving the character of the original design.

Pilot installation as proof of performance

Before proceeding with a full replacement, a pilot installation was carried out on site. Approximately 150 square feet of the existing wall were removed and renewed using the SemperGreenwall system.

Over the course of a full year, plant establishment, irrigation performance and overall system behaviour were closely monitored. The results were decisive. Vegetation established quickly and evenly, irrigation performed consistently, and the mineral wool growing medium proved highly resistant to the environmental pressures typical of dense urban settings. This successful pilot gave the Port Authority the confidence to move forward with the complete replacement.

Full-scale renewal

Following the pilot phase, Sempergreen Services was commissioned to renew the entire living wall. In total, 3,552 square feet of façade were transformed, incorporating approximately 25,700 plants across the full surface. The SemperGreenwall system was installed with pre-grown vegetation cultivated in a greenhouse, ensuring immediate visual impact from day one. The planting design closely follows the original layout, with subtle refinements to enhance long-term performance, seasonal variation and ecological value. Additional plant species were introduced to support flowering and biodiversity.

As part of the renewal, the entire irrigation infrastructure was replaced with a modern IMC web-based control system. This smart system enables precise irrigation, fertilisation and frost protection, all managed remotely. With continuous monitoring and automated alerts, plant health can be proactively safeguarded. This reduces maintenance intensity while ensuring consistent quality throughout the year, even under changing weather conditions.

The renewed living wall delivers immediate improvements in both appearance and performance. The non-organic mineral wool substrate eliminates conditions that can compromise plant vitality, while pre-grown panels provide full coverage without a lengthy establishment phase. To secure long-term quality, Sempergreen Services remains involved through an ongoing maintenance contract. This includes routine inspections, system monitoring and targeted plant replacement where needed, ensuring the wall remains healthy and visually strong over time.

A living wall built for the future

This project demonstrates how the SemperGreenwall system can serve as a reliable retrofit solution for existing living walls in need of a technical and ecological upgrade. By combining mineral wool-based Flexipanels, smart irrigation technology and pre-grown vegetation, the World Trade Center living wall is now equipped for long-term resilience in a complex outdoor environment.

Beyond its technical achievements, the wall continues to fulfil its symbolic role. Under Liberty Park, it remains a living green presence woven into daily city life, representing resilience, connection and renewal at one of the most meaningful locations in New York City.