More people than ever are living in cities, and accordingly, urban centres are ever-expanding. However, many cities and their residents are struggling with the multiple threats of the climate and nature crises, poor air quality, and worsening mental health. To try and combat these issues some cities are now looking to go green, literally! Whether we call it urban rewilding, greening, or even ‘depaving’, the idea is the same – to replace concrete with plants – and the benefits are huge. 

So, what are these benefits?

Greening our cities can have multiple benefits, for both people and the planet. Here are just some of the reasons why it’s time to go wild:

  • Cooling: The sheer volume of buildings, traffic, and people in cities creates an ‘urban heat-island’ effect, raising the local temperature. Plants and trees can help cool cities by up to 2.9°c. Just 1 single tree can cool as much as 10 air-conditioning units! 
  • Improved air quality: Vegetation absorbs pollutants and particulates much better than other surfaces, effectively cleaning our air for us. A Royal Horticultural Society study into urban hedges found that 1m of dense hedge can absorb the pollution produced by a car over a 500 mile drive. 
  • Improved water management: Green infrastructure in our cities can reduce flooding, reduce stormwater runoff, and help filter pollution, preventing it from reaching our rivers and oceans. Research has shown that greening our streets can help absorb and retain stormwater at a lower cost than other water control methods. 
  • Increased biodiversity: Urban development is one of the biggest threats to wildlife, but with careful planning, our cities can provide important habitats for a wide range of species. Cities that have created even small-scale green spaces have seen an increase in biodiversity, particularly amongst pollinators and birds, with new and even endangered species being spotted. 
  • Improved mental health: Studies have shown access to green space reduces stress and anxiety, lowers the risk of depression and helps with overall physical and mental wellbeing. Being more connected to nature also helps people engage more with eco-friendly behaviours.  

We’ve taken a curious look at some case studies from around the world which show just how incredible urban greening can be…

Medellín, Colombia

The Orquideorama in the Medellín Jardín Botánico. A series of wooden structures tower above a canopy of trees and plants.
The Orquideorama in the Medellín Jardín Botánico, by Oneil Williams via Unsplash

In 2016, due to rising concern over increasing temperatures and air pollution, Medellín launched the ‘Corredores Verdes’ (green corridors) 3-year programme. 

The $16.3 million project aimed to build 30 green corridors around the city, connecting streets, vertical gardens, parks, and the surrounding hills. This involved planting 8,800 trees and 90,000 plants. The corridors were designed to be as natural as possible, with canopies, mid-level, and low-level planting. They used carefully selected species of plants, for example the mango tree (Mangifera indica) chosen for its ability to absorb pollution, and other species chosen for wildlife. 

By 2019, research showed that average air temperature had gone from 31.6°c to 27.1°c, and average surface temperatures had dropped a staggering 10°, from 40.5°c to 30.2°c. 

As a result, Medellín was awarded the prestigious Ashden Award, recognising the success of the project which has achieved far more than its original aims. Beyond the significant reduction in temperature and improvement in air quality, the green corridors have resulted in a reduction in CO2, increased biodiversity, and a 35% increase in people choosing to cycle

The project has continued to grow since 2019, with the public voting for further investment in green projects. By 2021, a total of 880,000 trees and 2.5 million plants had been introduced , and Medellín now has around 4 million m2 of green space

Milan, Italy

Bosco Verticale. Two tower blocks covered in balconies planted with shrubs and trees.
Bosco Verticale by Mattia Spotti via Unsplash

Milan’s Bosco Verticale (Vertical Forest) apartment complex, built a decade ago, was one of the first architecture projects to place urban reforestation at the very heart of the design. Architect Stefano Boeri designed the buildings as a “home for trees that also houses humans and birds”. 

The buildings, which include 400 flats and an 11-storey office block, are completely covered by an incredible 21,000 trees, shrubs, and plants. The planting, installed on the building’s specially designed balconies, provides the equivalent of 30,000 m2 of woodland in just 3,000 m2 of surface. 

The success of this amazing design has since inspired many other urban reforestation buildings around the world, from the Netherlands to Cancun, and from Sydney to Los Angeles


Singapore Gardens by the Bay. A lush green park with a series of metal sculptures designed to look like trees.
Singapore Gardens by the Bay, by Sergio Sala via Unsplash

Singapore, a ‘city in a garden’, is leading the charge when it comes to urban greening. But transforming the city-state from a polluted, congested space to the garden city it is today required a serious commitment from the government. This meant a focus on long-term improvements rather than short-term economic gain, city-wide urban planning which included environmental considerations, and an emphasis on public awareness and youth education

Singapore works on the principle of ‘liveable density’, with community-centric towns interspersed with green and blue spaces. The island (only half the size of London) is home to 3 million trees, and even an area of virgin rainforest. There are strict requirements for new buildings to include green roofs and walls, and government funding for planting of existing buildings. 

Some of the most iconic examples of biophilic design (the practice of incorporating nature in the built environment) in Singapore are the Gardens by the Bay, where you can find the famous Supertree Grove, and even the airport, Jewel Changi, which is home to an indoor forest valley and gardens. 

Does size matter…?!

Major city-wide rewilding projects are fantastic (of course!) but that doesn’t mean that small changes can’t make a big impact. Check out some of these mini-greening projects:

Paris, France

Paris might be best known for the Eiffel Tower or the Louvre, but the city is also home to one of the world’s largest green walls. The 1,022 m2 wall of 15,000 plants, installed at the Quai Branly museum in 2004, includes 376 species from around the world. 

The wall was designed by Patrick Blanc, who is generally recognised as the inventor of the vertical garden, and who has also installed a number of other green walls around the city (and the world!).

Around the UK

  • Plantlife charity and non-profit Pictorial Meadows campaign for councils to plant wildflowers and reduce grass cutting, like in the beautiful Rotherham ‘River of Flowers’ project and on Peckham Rye common. 
  • Bee bus stops are popping up in cities around the UK, since proving popular in Leicester where 30 have been installed since 2019. The Wildlife Trusts are working with Clear Channel to install green-roofed bus shelters around the country, providing habitats and food for pollinators. 
  • Parklets (a parking space converted into a community space) have taken off, with the help of charity Possible, who provide advice and support for people wanting to convert one in their local area. Read more about parklets and their many benefits on the Groundwork website. 

Be curious!

  • Start at home; make the most of your own space, whether it’s a garden, a balcony, or even a window box. The Royal Horticultural Society and The Wildlife Trusts have some great tips. 
  • Check out whether there is a ‘depaving’, greening, or rewilding group near you that you can get involved with. For example, take a look at the urban rewilding work of non-profit Depave (based in Portland) and Green Venture (Ontario).
  • Discover some of the other cities prioritising the planet in the BBC’s article “Six Cities Making Room for Nature”.
  • Read more about the Biophilic Cities programme, Cities for Nature, and the Biodiverse Cities project. 
  • Read about other successful rewilding projects in our archives

Featured image by Jw. via Unsplash.