Published by City Farmer, Canada's Office of Urban Agriculture


Urban Agriculture on the Rooftop

Michelle Nowak
Phone: 724-349-8873
Cornell University
Senior Honors Thesis
May 2004

Below we have extracted the Table of Contents, Introduction and Conclusion to the complete paper which can be found here: Urban Agriculture on the Rooftop (PDF. 715K)

Table of Contents

1. Acknowledgements
2. Introduction
3. Overview of the Literature
4. Overview of Roof Garden Benefits and Challenges
5. Methods
6. Container Gardens
7. Green Roofs
8. Hydroponics
9. Toronto Case Study: Mountain Equipment Cooperative
10. Toronto Case Study: City Hall
11. Toronto Case Study: 401 Richmond
12. New York City Case Study: Earth Pledge Foundation
13. Rooftop Agriculture Throughout the World: Brisbane, Australia
14. Rooftop Agriculture Throughout the World: Senegal
15. Rooftop Agriculture Throughout the World: St. Petersburg, Russia
16. Rooftop Agriculture Throughout the World: India
17. Rooftop Agriculture Throughout the World: Montreal, Quebec
18. Rooftop Agriculture Throughout the World: Italy
19. Ithaca Case Study: Cornell West Campus Construction
20. Possibilities for Ithaca, New York
21. Conclusions and Implications
22. Appendix: Erica LaFountain's Roof Garden Journal


Rooftops are places of fantasy and imagination - places that sit above the din and chaos of the city, engaged with and yet apart from the city's motion. Rooftops yearn for the sky and yet are grounded to the city through the buildings which they top. What better place could there be for a garden? Or even better, a garden and a source of food? In this thesis, I will explore the topic of rooftop agriculture, one that has little comprehensive literature written about it. I will examine case studies and the potential for the expansion of roof gardens, as well as barriers to their successful implementation.

Cities have effectively driven out agriculture from their boundaries. Food systems today seem more and more nonsensical - the number of farmers is in constant decline, as large agribusinesses win the majority of government subsidies and increasingly learn ways to combine petroleum (or mechanization) and grossly underpaid migrant labor into food. Food arrives in the city from hundreds of miles away. It is often neither fresh nor good. Pesticides and preservatives may also diminish the health value of produce.

There is an urgent need for more sensible food systems. A countervailing movement in organic and local produce branches from the dominant agricultural trend. This movement is closely linked to the idea of food security, a term established at the 1996 World Food Summit, referring to the availability of "safe, nutritious, personally acceptable and culturally appropriate foods, produced in ways that are environmentally sound and socially just."(1 Rabinowicz, 2002. See bibliography throughout for more detailed citations.) The United States Department of Agriculture (USDA) published a report in 2000 stating that a total of 31 million Americans were food-insecure

in 1999, including 12 million children. (2 Ibid.) According to Nobel Prize-winning economist A.K. Sen, famine is not typically a product of inadequate food supplies; rather, it is more a consequence of the avoidable economic and political factors that lead to poverty and inequality.(3 Sen, 1981.)

One of the most vital components of this movement towards increased food security is a system of grassroots urban agriculture, grounded in community and school gardens. While urban agriculture cannot be relied upon alone to reduce hunger, it should be an important component of a comprehensive system of food security. Individual urban food production rarely confers self-sufficiency; more often it is a means to supplement one's diet with safe and adequate food. Through urban agriculture, city residents can learn to sustain themselves with food that they have produced with their own hands, but if urban food production is to reduce hunger and poverty, then it must also be part of a broader strategy.

Ultimately, urban agriculture should be coupled with other reforms aimed at reversing the concentration of agricultural production into fewer and fewer hands. This means supporting not only initiatives for urban agriculture, but also supporting small local farms and working to transform an unjust agricultural system in which large agribusinesses are subsidized at the expense of small farmers in and outside of the United States, and in which fossil fuel use and mechanization are overused, at the expense of global environmental and social health, in part because of perverse taxes and subsidies. Agricultural mechanization was widely implemented throughout the world during the "Green Revolution" of the 1960s and 70s, when the creation of improved wheat, rice, and corn that were more responsive to controlled irrigation and petrochemical fertilizers allowed for more efficient conversion of industrial inputs into food.(4 Collins et al., 2000.) As a result of the new seed varieties of the Green Revolution, agriculture globally produces tens of millions of extra tons of grain a year.(5 Ibid.)

Some celebrate the Green Revolution for having saved millions of lives from starvation by increasing agricultural productivity, and others lament it for having reduced agricultural sustainability and global environmental health. The issue is indeed complex: agricultural mechanization seems an inevitable product and continuation of the Industrial Revolution, and the reasons for its development are both good and bad. But we need to be aware of its dominance and effects, both direct and indirect. According to World Bank and Business Week analyses cited by Food First, global hunger has actually increased since the Green Revolution, proving that the increased outputs made possible by agricultural industrialization do not seem to solve problems of world hunger, as inequality and poverty prevent an appropriate distribution of food.(6 Ibid.)Wealthier farmers gain control of agriculture when the viability to succeed competitively depends upon purchasing expensive inputs. Not only does this harm small-scale, local agriculture and waste fossil fuels, it also seems to adversely affect health and food security. In North America, the average food product in the supermarket has traveled 1400 miles before ending up on the shelf.(7 Rabinowicz et al., 2002.)

Urban gardens can provide a forum for community connections in addition to the produce that they can provide. Urban gardens often serve as purveyors of tradition for immigrant communities, for instance when immigrants are eager to continue agricultural traditions that they left behind in their native countries. Community gardens may offer immigrants the opportunity to grow food that they are otherwise unable to access in North America. Urban gardens can serve as urban oases -- as vital green spaces that offer city residents a respite from the concrete along with opportunities to connect with the dynamic lifecycles of a garden.

Rooftops are often places of privilege; top floors of buildings often turn into penthouse apartments for the rich. The heights of buildings are frequently rarified spaces. This distinction follows a classical notion of hierarchy, illustrated by a pyramid - the peak can be an untouchable, extraordinary space that floats above the masses. This makes sense. Height means distance from the masses of the city. Height for skyscrapers confers prestige on a business that calls the building its own. Height is distinction. Height is fresh air and escape. Rooftops can flatten the hierarchy when they are accessible to all and particularly when they hold community gardens.

Rooftop gardens, as a specific urban agriculture niche set within a broader system of city gardens, enjoy their own set of distinctive benefits. Rooftops are underutilized and rarely-considered urban spaces with great potential for creative development. There are essentially three options for rooftop gardens. The first is container gardening, a less formal, cheaper form of roof gardening. In container gardening, few to no modifications are made to the existing roof structure; containers - anything from plastic swimming pools to recycled-wood planters - are placed on a rooftop and filled with soil and plants. The second type of roof garden, in which the rooftop actually becomes the planting medium, involves more intensive investments, but comes with its own set of advantages, including greater storm-water retention, building insulation, and the formation of patchwork urban "stepping stone" ecosystems, which work to reverse the fragmentation of ecosystems that follows urbanization by offering temporary habitats to fauna such as birds and butterflies during their long migrations. The third rooftop garden possibility is rooftop hydroponics, in which plants are grown in a soilless medium and fed a special nutrient solution. Rooftop hydroponics can be the lightest of the three options and may offer the possibility for faster plant growth and increased productivity.

Conclusions and Implications

Despite having many benefits, roof gardens face clear challenges to their widespread application, in all of their forms - container gardens, green roofs, and hydroponic gardens. The most significant are issues of access and roof load capacity. These barriers are especially problematic in liability-obsessed countries like the United States, although concerns for safety and building protection are certainly valid. Lack of knowledge or incentives, funding, water supply, safety, and the harshness of rooftop environments are also major barriers. Still, rooftop agriculture is slowly becoming more common, particularly in the developing world, where rooftop food production may have a significant impact on food security and income, solutions are creative and site-specific, and roofs are often built of different materials than those in the developed world. The green roof industry is quickly gaining visibility and respect in North America, and a few cities, including Portland (Oregon), Toronto, Chicago, and New York, are beginning to create incentives for green roof construction. Still, we are a long way from the kind of progress that has been made in Switzerland and Germany.

It is unfortunate that so many green roofs are not built for accessibility, because inaccessibility prevents the realization of a great deal of rooftop potential. Without accessibility, green roofs serve many impressive environmental functions, yet additional community or food security benefits are lost. The inaccessibility of green roofs, of course, makes sense in light of cost constraints and liability concerns. The most ideal form of rooftop agriculture, in terms of its potential to maximize ecological, agricultural, and community benefits all at once, is in fact green roof agriculture. With the rapid expansion of the North American green roof industry, expansions for green roof agriculture might also expand. Of course, green roofs are also the most expensive of the three types of roof gardens, and, for that reason, are not a possibility for many sites. Nor do they make sense in all situations - where people have created a rooftop garden system that they can build out of local materials and repair and maintain themselves, as in Senegal, India, and St. Petersburg, they use their intimate knowledge of local conditions and available materials to design elegant, simple systems that increase their self-reliance. But one would hope that as municipalities, states, and nations learn the advantages of creating incentives for green roofs, even now-unlikely green roof projects will become possible. Along this vein, affordable housing organizations are working with Earth Pledge Foundation's Viridian Project to bring green roofs to underserved housing communities in Chelsea, Harlem, and Brooklyn, all of which are to be completed by the summer of 2004.(92 Cheney, 2004.)

Rooftop food gardens work best atop buildings where food is consumed or processed - at 401 Richmond, for example, on an office building which houses a cafˇ, near restaurants in Brisbane, Australia, and atop houses or apartment buildings in Senegal, India, Italy, Montreal, and St. Petersburg. When land at grade-level becomes available, food is not consumed close to the roof garden, or garden care has not been well coordinated, rooftop agriculture has been less successful, for instance at Toronto City Hall's permaculture and kitchen garden green roof plots, on the Field to Table/FoodShare warehouse in Toronto, or with the brief herb plantings that Peter Carr-Locke did on MEC-Toronto's green roof. In countries like the United States, where food costs for many people are only a small part of income and most don't feel threatened about their food supply or safety, few people will take the initiative to begin rooftop agriculture projects. But those that do will create projects, whether short or long-lived, that spread a bit of the enthusiasm for the potential that roof gardens can have - and, just as urban community gardening has grown tremendously within the past decade, into a real, vibrant movement -- so might rooftop agriculture. Erica and I, regardless, will continue to look hard for a roof on which to try out our ideas.

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Revised Thursday, July 15, 2004

Published by City Farmer
Canada's Office of Urban Agriculture