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One of Singapore’s many rooftop gardens (Photo: Getty Images / Design: Tina Tiller)
One of Singapore’s many rooftop gardens (Photo: Getty Images / Design: Tina Tiller)

ScienceJune 13, 2023

The case for more greenery in our urban jungles

One of Singapore’s many rooftop gardens (Photo: Getty Images / Design: Tina Tiller)
One of Singapore’s many rooftop gardens (Photo: Getty Images / Design: Tina Tiller)

Rooftop and vertical gardens can soak up rain and reduce searing heat. They look good, too.

This is an excerpt from our weekly environmental newsletter Future Proof brought to you by Electric Kiwi – sign up here.

Watching the Netflix series Sweet Tooth recently, it was neat to see the buildings and streets of Auckland – where the show was filmed – draped in more greenery than usual. Of course, in the show it’s meant to signify the post-apocalyptic state of the city… but facades cloaked with vegetation might also be a part of our climate-positive future.

Take Singapore, for example. In the dense, tropical metropolis, multi-storey buildings are clothed in lush vertical gardens and green roofs in an effort to keep interiors cool, reduce the urban heat effect and quell air pollution. New developments are incentivised to incorporate such greenery – not just for the practical benefits, but also because it’s aesthetic and enhances residents’ connection with nature. Singapore wasn’t always like this: 95% of its original vegetation was cleared following the city’s founding in 1819. It’s taken decades of careful urban planning and a strong vision for a “city in nature” to achieve its status as one of the greenest cities in the world. Today, Singapore has 47% park and garden coverage.

Closer to home, in Tāmaki Makaurau, Auckland Council installed its largest living roof atop the Central City Library last year. More than 2,000 plants were propagated by Ngāti Whātua Ōrākei and planted out on the roof. A year on, the Council says the hardy natives are “thriving”. The living roof is being closely monitored by Council ecologists and researchers from the University of Auckland, to assess how it’s performing through gnarly weather conditions. Results will reveal just how much rainfall this “living infrastructure” can soak up (possibly 5-10 litres per square metre), and which native plants are most suited to high rise life.

In Wellington, architecture PhD candidate Maggie McKinnon is testing out our native plants’ ability to cling on in cascading vertical gardens, battered by the rugged winds that are typical of the capital. She’s also investigating whether hanging gardens could benefit and boost urban biodiversity, especially birds, as well as how the greenery might even be able to buffer said wind. The RNZ podcast Our Changing World interviewed McKinnon last year about her project. And Your Home and Garden has a DIY guide for creating hanging gardens, if you’re a keen gardener with wall space to spare.

An experimental native garden on the roof of Auckland’s Central City Library. (Photo: Auckland Council/Supplied)

Perhaps we can craft better green spaces at ground level too: Professor Rod Barnett, head of the Wellington School of Architecture, argues that gardens should become “living labs” where researchers could figure out how to boost the carbon-capturing prowess of suburban backyards.

As New Zealand cities build up, it might be useful to take a leaf from Singapore and incorporate nature into denser designs. I’m looking forward to a future city that’s less concrete jungle, more lush biodiverse paradise.

Keep going!