Vertical gardens are particularly suitable for cities, where the plants reduce overall temperatures of the building and utilize available surface area. The primary cause of heat build-up in cities is insolation, the absorption and storage of solar radiation by roads and buildings in the city and its subsequent re-radiation. Plant surfaces however, as a result of transpiration, do not rise more than 4–5 °F above the ambient and can be cooler. Vertical gardens are optimal for reducing water use and purify slightly polluted water by absorbing the dissolved nutrients; bacteria mineralize the organic components to make them available to the plants. Suitable in arid areas, circulating water on a vertical garden is less likely to evaporate than in a horizontal one.
“There is an increasing focus on air quality in cities, and green walls are one way of combating pollution within the micro-climate of a particular building.” London’s Mayor Sadiq Khan
Urban vertical gardening has gained traction in the last decade with increasing support from city officials, community leaders, and governmental organizations. Rapid urbanization and reduction of rural areas adversely affect our agricultural infrastructure. Vertical gardening techniques have emerged as a result of the reduction of horizontal space and increased efficiency as fresh food can now be produced from the sustainable urban model. Most urban centers across the United States do not have access to local, fresh produce. Food is transported to city centers by the truckloads from hundreds and even thousands of miles away. Oftentimes, these materials arrive close to or past their expiration and the condition of the food is questionable. As a result, city residents, which account for 80% of the US population, are provided with low quality produce.
As density in cities increase, green areas whether on the ground or on the walls – become ever more valuable. For many city dwellers going about their busy everyday lives these green spaces provide a breath of fresh air in more ways than one.