Along a 27-mile double-decked ring road, about 8 million plants are growing on roughly 2,000 concrete columns, turning bare infrastructure into vertical gardens visible to drivers.The planting covers around 15 acres of that concrete. Instead of planting trees on the ground, the project uses the columns because the land beneath the elevated road is permanently shaded, has utilities below, and offers little room for conventional planting, as per a report. The project began with just 10 pillars before expanding into a much larger program.
Why the plants are growing on concrete columns
The land beneath an elevated ring road is not an easy place to grow trees.Little direct light reaches the ground, while utilities below and the elevated road above leave limited space for roots. A mature tree could also interfere with the foundations supporting the structure.The columns offer a different option. They are already owned by the city, provide large vertical surfaces and do not require additional land. Rather than creating new planting space, the project makes use of infrastructure that was already there.
The gardens grow without soil
The vertical gardens use hydroponic felt pouches made from recycled aluminum and plastic packaging, as per The Pulse report. The material weighs much less than an equivalent depth of soil, reducing the load placed on the concrete columns.Water comes from the road above. Rain falling on the elevated deck and road drainage is collected and filtered before being sent through drip lines to the plants. Sensors monitor moisture on individual columns and flag areas that are becoming too dry. The system uses runoff that the road was already producing to help water the plants.
How the project is funded
The project is funded through advertising rights rather than city money. A digital billboard is placed on one column in every 15.The founder has acknowledged the role of corporate sponsorship, saying, “I’m cleaning” a soft drink company’s soul and that the project cannot solve everything at the same time, as per The Pulse report.
The project has also received strong public support. A survey of 27,000 residents found that 98.5% were in favor. For drivers, the gardens provide a very different view from the bare concrete columns that previously lined the road.
Critics say ordinary trees could do more
The biggest criticism is the cost.
Critics argue that the same money spent on vertical gardens could buy more conventional street trees, providing more shade and canopy at ground level.
