Whether in our homes, workplaces, private gardens, or public landscapes, the question of sustainable development leads to endless discussions of what the expression really means. Each explanation proffered requires that we establish for a project one or more goals that might help us enhance our stewardship of the planet. In some situations, however, these goals may be at odds with each other.
Two recent projects in San Francisco provide plenty of opportunity for debate on the sustainability question. The California Academy of Sciences unveiled its living roof in 2008, and draws daily crowds to its rooftop viewing platform to see both the native meadow and the wildlife attracted to it. Not far away, Drew School’s new vertical garden, just completed in spring 2011, also features California native plants—exclusively—in a three-story planted wall. Designed and planted by Patrick Blanc, the Parisian who introduced vertical gardens to the world, this is the first example of California’s native plants used in such a cutting-edge manner—and among the largest vertical gardens in the country.
While such planted roofs and walls may be aesthetically appealing, the water necessary to keep native plants thriving in an arid climate is certainly greater than for the same plants in the ground; maintenance of such “artificial” gardens is likely to be more challenging, even beyond the establishment phase. Yet, the primary goals of living roofs and vertical gardens such as these are to extend the life of a building’s structure, to reduce the need for heating and cooling of interior spaces, to help cleanse the air and lower the heat-island effect, to reduce rainwater runoff, and to replace habitat lost to construction. That’s a pretty decent potential return on an investment of water resources and manual labor.
As Stephen Orr suggested in the Garden Conservancy’s recent seminar on How We Garden NOW (co-sponsored by Pacific Horticulture), we are still in the early stages of a steep learning curve on sustainability. We’ll be following these two San Francisco projects to see what we can learn about sustainability. At the least, we’ll certainly learn more about the adaptability of our native flora for the built environment—and that’s a good thing.
Richard G Turner Jr