The vertical gardens around Metro pillars, once touted as the city’s new-age attempt to green itself, are wilting and dying.

The gardens had been set up on the pillars of the under-construction Airport-New Garia Metro line along New Town's Major Arterial Road — from the box bridge in Mahisbathan that connects Sector V and New Town to City Centre II.

The pillars now resemble movie props from a ghost town with dead plants sticking out of their pots.

The New Town Kolkata Development Authority (NKDA), which provides civic services to New Town, started setting up these gardens after getting the go-ahead from the railways in 2019.

The NKDA was also in charge of watering and maintaining the gardens.

The Rail Vikas Nigam Ltd (RVNL) is the implementing agency of the 29km Airport-New Garia Metro corridor, also called the Orange Line.

A senior NKDA official said they had sent a letter seeking a renewal of the agreement and permission from RVNL to maintain the gardens but the request had been turned down.

In its reply, the RVNL allegedly cited fears of structural damage affecting the load-bearing capacity of the pillars and security concerns.

“Since we have not got permission from the implementing agency of the Metro corridor in New Town, we cannot continue to water them,” NKDA chairman Alapan Bandyopadhay told The Telegraph.

The gardens were built by placing mats capable of retaining water for several hours around each pillar, and then small pots with saplings were installed on them.

Truck-mounted pumps and drip-irrigation methods were being used to water these plants.

Bryophyllum pinnatum, or air plant, various ferns and flowering plants that can survive on little water and minimum maintenance had been planted.

A senior RVNL official said they did not allow the New Town authorities to continue watering the gardens as the load-bearing capacity of the pillars could be compromised by the added weight.

“Apart from the fact that gardens have a weight of their own that can affect the load-bearing capacity of a pillar, seepage from watering the plants might result in the concrete getting damp. If the New Town authorities want to set up such gardens they should make separate structures for them,” said the official.

However, Gokul Mondal, who teaches construction engineering at Jadavpur University, said the load because of plantation in the vertical gardens was negligible.

“The weight of the gardens around each pillar is negligible considering the pillars’ load-bearing capacity. Even if watered, the load in each bucket will go up marginally. This should not have any effect on the pillars’ strength,” said Mondal.

According to him, the chances of the pillars getting damp were minimal. The grade of concrete that should be used to construct high-load bearing pillars like for Metro has low porosity or water permeability.

“These pillars are designed to withstand the elements and to remain unaffected by extreme weather conditions,” said Mondal.

Environmentalist Subhas Dutta said it was both objectionable and sad that so many gardens in an urban area had been left to die out.

“If these pillars cannot bear the weight of saplings then I wonder how they will bear the load of a Metro train. This is highly objectionable and the railway authorities must be answerable for this,” Dutta said.

In New Town, more than 300 plants had been accommodated on each of the pillars, each of which is around 30ft high.

A single such garden on a Metro pillar can release more than 500 litres of oxygen every day, an NKDA official said.