I. What is a Rooftop Garden?
A rooftop garden refers to the green space created by planting flowers, trees, and other vegetation on the top of various buildings, including rooftops, terraces, or balconies. These gardens are also designed with various landscaping elements, transforming unused or underutilized rooftop spaces into thriving green areas.
In today’s rapidly advancing society, the importance of environmental sustainability has become more prominent than ever before. Modern architecture is increasingly characterized by densely packed, multi-story buildings with flat roofs. However, as urban development progresses, environmental issues have also intensified. Improving ecological conditions and increasing green space have become universally recognized goals across the globe. As a result, cities are focusing on maximizing green spaces by utilizing every possible area, including the development of rooftop gardens, which has become a significant aspect of urban construction. The advancement of modern construction technologies has further facilitated the creation of these rooftop gardens.
II. The Origin and Development of Rooftop Gardens
A. The Origin of Rooftop Gardens
Rooftop gardens are not a modern invention; their origins can be traced back to before 2600 BCE. The Hanging Gardens of Babylon, one of the Seven Wonders of the Ancient World, is considered one of the earliest examples of a rooftop garden. In ancient Babylon, plants and trees were grown on tiered artificial platforms, and streams were diverted to the top of these platforms, creating artificial waterfalls and a true garden environment. Although these ancient gardens did not account for issues like load-bearing and soil thickness, they did implement early waterproofing techniques, such as using lead sheets and branches soaked in tar as moisture barriers and filtration layers. These methods laid the scientific groundwork for future rooftop garden construction.
In ancient China, building materials were primarily wood, and roofs were often steeply pitched, making them unsuitable for creating rooftop gardens. As a result, there is little historical evidence of rooftop gardens in China. However, records show that trees were planted along the Great Wall, including rows of pine trees at Shanhaiguan and other species at Jiayuguan, which might be the earliest Chinese records similar to rooftop gardens.
B. The Development of Modern Rooftop Gardens
The construction of modern rooftop gardens involves addressing several challenges, such as load-bearing capacity, waterproofing, plant selection, and public perception. These challenges have undoubtedly hindered the development of rooftop gardens. The world’s first true rooftop garden was built in 1959 in Oakland, USA, covering an area of 12,000 square meters. This garden utilized lightweight growing media, with trees planted on support columns, primarily using shallow-rooted species and herbaceous plants. These methods were key to its success.
Chinese garden design has greatly influenced global landscape architecture, yet China has been relatively slow in the development of rooftop gardens.
