Along a 27-mile ring road, 8 million plants are climbing 2,000 concrete columns, fed by recycled rainwater from the road above, turning 15 acres of dead infrastructure into vertical gardens seen by drivers

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.

There is also a question of who sees the gardens. Because the columns stand along a ring road, drivers are the main people who experience the planting visually.

The project's reported air-quality figures have also been described as promoter figures rather than independent measurements.

Plant losses are another consideration. Around 10,000 plants have been lost. The project's own account describes this as a very small share, although compared with the number planted, it works out to roughly one plant for every 800.

The idea is to use infrastructure differently

The project is not presented as a way to clean an entire metropolis.

Its narrower idea is to put plants on surfaces that have no competing use. Concrete columns beneath elevated roads are one example, while retaining walls, noise barriers, and the sides of parking garages can provide similar publicly owned surfaces.

The challenge is keeping the plants alive.

A tree can survive periods of neglect, while plants growing in felt pouches about 20 feet above the ground require regular attention. The gardens therefore depend on ongoing maintenance rather than simply being planted and left alone.

Still, the transformation is visible. Bare concrete columns have become planted surfaces, with hydroponic pouches made from recycled materials and irrigation supplied by collected rainwater and road drainage. What was once simply part of the structure carrying traffic now also supports vertical gardens.