This article appeared in the Spring 2011 issue of the Permaculture Activist magazine.
“Right smack dab in the middle of town/
I’ve found a paradise that’s trouble proof/
Up on the roof. . .Up on the roof. . .”
Along with the cultivation of vacant lots, rooftops represent the single greatest opportunity for expanding urban food production. This is particularly true in dense urban cores, where vacant land is less available and adequate light for ground-level food growing is limited by the shade of tall buildings and street trees. Most urban roofs can support some container growing and, with some engineering assistance, many roofs can actually support significant food production capacity. The following survey of rooftop food-growing in Philadelphia and elsewhere reveals some of the possibilities.
The potential for rooftop food production in cities is tremendous. GIS data from PASDA reveals that there are 162,000 buildings in Philadelphia with a total rooftop area of over 16,000 acres. According to Peleg Kremer, who is completing a dissertation on food production in the city, if even 0.5% of this area were adapted for food production, it would “exceed all the urban farms and community gardens currently in use”. New York Sun Works has estimated that there are 14,000 acres of unshaded rooftops in NYC that could feed up to 20 million people if converted to hydroponic food production. I suspect that their estimate doesn’t account for the actual suitability of the roofs for that usage, but even a small percentage would result in a very impactful increase in urban food self-sufficiency. Gotham Greens won first prize in New York’s Green Business Competition in 2010 and is in the process of constructing a 12,000 SF hydroponic rooftop farm that is expected to produce 30 tons of fruit and vegetables a year. To a Permaculturist, of course, hydroponic systems scream out for polycultures with accompanying fish production.
Rooftop food growing needn’t be as expensive or energy-intensive as Gotham Greens’ 1.4 million dollar venture. It can be as simple as placing a few planters or containers on your roof. A couple years ago I assisted a family in setting up a container garden on top of their garage. Although the property did include a small backyard, it was too shady for vegetable production- a very common problem in the city. We set up a series of containers all along the load-bearing walls, with a total combined planting area of around 60 SF watered by a drip irrigation system on an automated timer. The roof was planted with a variety of vegetables and herbs and even a couple dwarf blueberry bushes. The whole installation was completed for no more than a couple hundred dollars in materials costs. Although it is necessary to consult with an engineer before any rooftop installation, most roofs can handle a minor addition of weight in the form of a few planters.
The Philadelphia Rooftop Farm (PRooF) partnered with the Community Design Collaborative (CDC) in 2010 to explore the possibility of farming a diverse assortment of residential roofs in the city. The idea being pursued by PRooF is the conversion of otherwise wasted residential roof space into food production, with the homeowners receiving a share of the produce and the rest being either sold or donated to emergency food services. The CDC’s team of architects, engineers, and designers created a detailed report on all aspects of the project’s feasibility. This included a design for a prototype self-watering container constructed from corrugated polypropylene boxes (available commercial versions are prohibitively expensive for a project of scale). It also analyzed 10 proposed residential roofs in the city and found that rowhomes, which comprise a majority of Philadelphia housing stock, have much greater potential for rooftop production than twins or singles. The report includes several alternate designs for residential rooftop farming, employing both containers on the roof and beds built into roof decks straddling party walls.
My overall conclusion from reading the CDC’s report for PRooF is that the costs and difficult logistics of such diffuse production are likely prohibitive for a commercial or even non-profit venture as proposed. However, the detailed report should be useful for homeowners looking to produce on their own roofs, for whom legal and accessibility issues are less of a challenge. Additionally, the strategy can and should be easily adapted from single family homes to use on larger structures, like commercial, industrial, and apartment buildings. Such are more frequently over-engineered for rooftop capacity, often have much easier existing roof access, and present a more efficient concentration of larger production space. NYC already features two such rooftop farms of over an acre in size, the Eagle Street Farm in Brooklyn and the Brooklyn Grange Farm in Queens. Milwaukee is the home of Community Growers, the world’s first rooftop CSA. There is certainly great potential for this in Philadelphia. Indeed, the Cloud 9 Rooftop Farm is currently raising funds to get their operation started on the 3 acre rooftop of the SHARE Food Program warehouse in the West Allegheny neighborhood. In addition to all the buildings in use, the city also features the low-hanging fruit of more than 700 abandoned factories. These relics of the Philadelphia’s industrial past are begging to be re-imagined with rooftop farms and floors of aquaculture, mushroom, and vermicompost production, perhaps combined with mix-use residential, artistic, and commercial loft space.
It is a natural fit for restaurants interested in the local food movement to begin to enhance their cuisine with produce from gardens located above their patrons’ heads. Chicago’s Uncommon Ground restaurant supplies their kitchen from a half-acre mini-farm on its roof, the first ever certified organic rooftop farm. Although the produce grown there represents only a fraction of the total used in the kitchen, it is not an insignificant contribution and has generated considerable interest and awareness with the public.
Grace Wicks, a Philadelphia garden designer, has been developing rooftop food production with a series of restaurants in Center City. I visited a couple of the roofs with her in the fall of 2010. At Noble, you could look up from your dining table and see some of the garden beds framed in the skylights. Their roof featured 3 long herb beds of approximately 15 feet by 2 feet, each with a different theme: lemon (lemon grass, lemon verbena, lemon balm, etc), herbes-de-provence (basil, thyme, lavender), and edible flowers (calendula, borage, nasturtiums, etc). There were also a series of individual containers in which tomatoes, basil, and a variety of peppers were grown. The Noble garden was tended by the cook staff and its produce is incorporated into the menu. Once a month the restaurant hosts a small private rooftop dinner with a special menu created by the head chef based upon the flavors of the roof. Sadly, Noble has since disappeared from the fickle scene of Philadelphia restaurants.
Wicks has also worked with the 4 Seasons, a large luxury hotel featuring the fine dining Fountain Restaurant. The engineering department at the hotel has made some interesting strides towards sustainability, including using co-generation from its natural gas heating to provide 30% of the building’s total electricity use. A hotel-wide composting program was instituted in 2007 and in 2010 their own compost filled a series of raised beds on the ample roof of the building. Besides a wide variety of herbs and vegetables, the roof plantings include strawberries, blueberries, and hardy kiwi vines. The head chef is also the head gardener and works the produce into restaurant specials (rooftop blueberry pancakes, sky salad, etc).
THE ENGINEERED APPROACH
New buildings can be engineered to hold additional rooftop weight, thereby allowing a significant increase in urban food production by moving it overhead. I recently had the pleasure of designing rooftop gardens for Sheldon Crossing, a new platinum-LEED townhouse development in the Manayunk neighborhood of Philadelphia. In addition to geothermal heating, solar panels, and other green features, the homes were engineered to support the weight of 15” of soil on their roofs. This is enough depth for genuine gardens, including a native grass lawn, perennials, shrubs, and even small trees. I created 15 alternate plans for the site, varying from entirely edible landscapes to Japanese gardens to modern minimalist styles. Unfortunately LEED standards credit only all-native plantings and this limitation was imposed on the final plan installed on the show unit. The final design included a mostly open lawn of native grasses in the front section overlooking the city and a walled stroll garden of native plantings in the back. The back garden does include a Juneberry (Amelanchier), admired for its ornamental qualities as well as its fruit. Another 15 units are proposed and I’m hopeful that some of the more edible-intensive designs will be chosen by some of the buyers. One would also hope that the LEED standards are revised at some point to also recognize the environmental value of edible landscaping.
Interestingly, Philadelphia also features a remarkable historic rooftop garden. Architect Clarence Siegel designed the Garden Court Plaza in the late 1920’s. Four tall, opulent towers were intended, connected by a large parking garage with a private park for residents on the roof. Only one of the towers and the parking garage were completed when construction was halted by the stock crash in 1929. I recently visited the rooftop park with a friend who lives in the tower and one can imagine it as it was, with wide lawns, trees, gardens, and an ornate central pond. The roof totals more than an acre in size and appears to have at least 18” of soil. A couple dozen of the residents currently grow vegetables and flowers in garden plots on the roof, but it is primarily used for cookouts, soccer games, and recreation. A few ornamental cherries remain and ducks visit the pond seasonally. Certainly there is potential for a great deal of food production there and if this could be engineered in 1929, the possibilities for today seem encouraging.
BEEKEEPING & ROOFTOP LIVESTOCK
Folks have been beekeeping on urban roofs for centuries in Paris, London, and the other capitals of Europe. Honeybees are the most sensible livestock for urban rooftops. Cities are actually surprisingly excellent places for honey production because of the diversity of landscape plantings, weeds, and high pollen availability from the preponderance of male trees. Urban honey indeed fares well in taste tests. Housing bees on rooftops keeps them largely out of the way of humans- I’ve been beekeeping on a friend’s rooftop in West Philadelphia for a couple years and no neighbors have noticed or commented. It seems eminently feasible for cities to be self sufficient in honey production. Of course, bees also provide many other benefits including free pollination services, wax, and other value-added and medicinal products. (See my previous article about urban beekeeping for more information).
There’s been an explosion in hobby (small scale, non-commercial) beekeeping in recent years. The Philadelphia Beekeeper’s Guild was formed about a year ago and membership is now approaching a hundred, the majority of whom are new beekeepers. In West Philadelphia, a gourmet food shop called ‘Milk & Honey’ started an initiative this year in which customers signed up to host hives in their yards or on their roofs. Some of the honey was given to the hosts and the rest is sold at the store, with a percentage of profits going to support the Philadelphia Orchard Project.
Honeybees are not the only viable livestock for roofs. One of my favorite stories from a friend’s recent visit to Havana was of a rooftop meat farm. Rabbits and guinea pigs (commonly eaten in parts of the Caribbean and Latin America) were being raised on a rooftop, largely fed by grass clippings from a baseball field across the street. There is also a culture of raising pigeons on urban roofs in NYC and other cities- perhaps these should be considered for potential food production. Worms for vermicomposting would seem another rooftop possibility, although perhaps a better choice for cellars.
WHY ROOFTOP FOOD-GROWING?
The more food production that can be accomplished within cities, the more outlying areas can be retained or restored to the natural ecologies that support us all. Urban food production results in multiple ecological benefits. The more locally food is produced, the lesser the environmental impact in terms of transport and the lesser the degradation of nutrient density due to transport time. What could be more local than the roofs over our heads? Rooftop food production is also by necessity primarily small scale and intensive, thus avoiding the devastating environmental impacts of industrial, large-scale farming.
Expanding our food self-sufficiency will become increasingly essential as our present system of global, industrial food production becomes increasingly costly and unsustainable due to increasing demand and declining fossil fuel supplies to support it. Cities are defined by their population density and this ratio of people to land makes them especially food insecure and vulnerable to future disruptions in supply.
Although cities are unlikely to ever produce all of their own food, significant contributions are certainly possible. During World War II, urban victory gardens provided 40% of the produce consumed in the United States. This is not an unreasonable number to attain again. Following the collapse of the USSR and its sudden plunge into a post-industrial economy, Havana Cuba experienced years of hunger and difficult transition to a more self-sufficient agriculture. The city now produces the majority of its own food in 30,000 community gardens and numerous rooftop gardens. Cities across the globe need to undertake a similar transformation before it is forced upon them. Rooftops are important place to start, as they represent a unique opportunity to expand food production without displacing other important urban functions.
In an overpopulated world straining the limits of its natural resources and carrying capacity, one can argue that the most important function of cities is to house as many people as densely as possible. The more people that can be housed in cities, the more outlying areas can be shifted to food production and/or natural(ized) areas that provide the ecological functions that support us all (clean water, clean air, sustainably harvested wood, wild foods, etc). Dense cities also allow for significant per-capita energy savings in personal transport through walkability, bikeability, and the feasibility of public transit systems. These energy savings are compounded by reduced heating and cooling costs due to larger building sizes, smaller living spaces, and shared walls. In fact, as the most densely populated piece of land in the United States, Manhattan ranks dead last in terms of per capita energy consumption.
If you are not a farmer of manager of natural lands, it is probably better for the earth if you live in a dense settlement. The suburbs are for the most part an ecological disaster or, as James Kunstler proclaims, “the greatest misallocation of resources in the history of civilization”. If we are to attempt to transition to a post peak energy world, I would posit that now is the time for a genuine Back-to-the-City movement. Such a movement has already begun, as evidenced by the recent revitalization of many urban cores and the slowing and even reversing of urban population loss in many American cities. These cities need creative urban farmers and thoughtful Permaculture designers to rebuild and renew them and make them as livable and self-sufficient as possible.