Urban Renaissance Institute

Lawrence Solomon
National Post
November 13, 2004

Cities are the once and future centres of agriculture. That’s true in spades for cities that are chic and sophisticated, and chock-a-block with people.

Paris until a century ago was an agricultural powerhouse, producing some 110 pounds of produce per person per year in the area known as Le Marais, now a trendy district of residences and museums. Other major cities, on both sides of the Atlantic, were also large food producers, meeting much of their own food needs and exporting their specialties to each other. But Paris was in a class by itself, not only because of the scale of its operations – one-sixth of its area was turned to food production – but also because it perfected the high-input, high-profit, niche farming phenomenon known as la culture maraichere. During its heyday from the 1850s to the late 1880s, a period during which its population doubled from one to two million, this intensive form of market gardening produced more than 100,000 tons a year of lucrative, out-of-season salad crops as well as other vegetables, fruits and flowers. Much of this cultivation employed advanced greenhouse technologies, occurring under glass-covered frames and bell-shaped glass cloches that trapped the warmth of the sun.

London, a more populous city, was less of an agricultural power, not because it lacked technology – England had launched the Industrial Revolution – but because it lacked an essential present in Paris: an appetite for fine food in a great number of citizens willing to pay a handsome premium for it. In the Paris market, competition for fresh produce was so acute that, for example, a mere one-day delay in getting apricots to market cost one-seventh the sale price. This demand for culinary excellence drove innovations that let the Paris maraichers overcome the chief impediments to farming in the city, namely the high cost of urban land and other inputs.

The maraichers’ solution lay in replacing the technology of the farmer – the plow, the horse – with that of the gardener. To get more produce out of each tiny plot, Parisian gardeners germinated seeds separately, then transplanted them into beds of loam, often under glass, to develop their rootlets. Sickly plants would be discarded and successful ones bedded in the scarce, open ground, where they would be tended until ready for next day, and often same day, consumption. Using this intensive method of cultivation, Paris gardeners obtained three to six growing seasons in a city that had been considered “two degrees of latitude” too north to grow vegetables year round.

The heat needed to emulate the soils of more southerly climes came only partly from the sun. Horse manure – 100,000 tons of it a year, much of it from the city’s extensive horse-drawn public transit system – not only formed new soil and provided nutrients but, more importantly, warmed the soil as it fermented. Carbon dioxide from the fermenting manure also aided plant growth. Water, a commodity often scarce in cities, came from the sewers, pumped by steam engines through the maraichers’ personal irrigation pipes.

The rise of public transit, in effect, fuelled an urban farm industry, but improvements in public transit also spelled the farm industry’s demise. When motorized vehicles replaced the horse-drawn car, urban agriculturalists lost their cheap fuel and fertilizer. Coupled with the high cost of city land, urban farming was doomed. By World War I, Paris’s once plentiful market gardens – 1,800 of them on 3,500 acres at their peak – had all but disappeared. In other western cities, urban farming also died out.

Yet urban agriculture has never lost its potential, as can be seen in affluent Hong Kong, the world’s densest city. Because Hong Kong’s Chinese population places a high premium on fresh produce and freshly killed animals, the city produces two-thirds of the poultry, one-sixth of the pigs, and almost half of the vegetables eaten by its citizens and visitors on about 5% of the city’s land. Dense, affluent Singapore, which even farms between highrises, similarly shows agriculture’s viability: Singapore’s 10,000 urban farmers produce 80% of the poultry and one-quarter of the vegetables consumed locally.

Without the zoning laws that now outlaw agriculture in western cities, and without the subsidies to inefficient rural agriculture, many of our cities, too, would see farms on underused lands. Urban farming could be ubiquitous in cities, including in dense downtowns, by tapping into free energy, free water, and free land that now goes wasted.

The city’s abundance of plots, suitable for growing fruits, vegetables, and flowers, are found atop its office towers, condos, and apartment buildings. There reside the buildings’ heating and cooling systems which are often placed on roofs to dispose of their waste heat, among other reasons. Greenhouses located next to this roof equipment, or on platforms built above the equipment, could capture an inexhaustible amount of waste heat year-round, giving them a competitive advantage over rural greenhouses, whose energy costs are often their single-biggest operating expense. Rooftop greenhouses, as well as open-air plant beds, would have other advantages, too. Their produce could be delivered by elevator directly to stores and restaurants at ground level, and to customers within the buildings, rather than requiring trucking and warehousing. Unlike rural farms, which often vie for water with residential and recreational users, urban farms would tap into plentiful supplies of treated “grey water” – the waste water from kitchens, washrooms, or other facilities suitable for irrigating plants. Pumping grey water up to roof nurseries instead of disposing of it by sewers, and diverting rainwater to roof crops instead of carrying it down pipes below ground, would also relieve pressure on municipal water works. Only one major impediment prevents rooftop farms: urban zoning laws that ban commercial agriculture in cities. Rescind the laws and plantations would become a fixture of the urban skyline.

As it is, many high-end restaurants already plant at roof level – it’s legal to do so if they use their crops in their own operations – and hydroponic gardening and balcony crops have become a billion-dollar industry. Vegetation atop buildings provides environmental benefits. In many European cities, these “green roofs” are used to insulate buildings from heat and cold, cleanse air of pollutants, and prevent roof runoff from entering the sewer systems. These amenities also save money for the building owners and for society as a whole, largely justifying the expense of the green roof installation and convincing many North American cities to join the trend. One more amenity – fresh, high quality produce – would put the economic calculation over the top.

This is last of a series; Lawrence Solomon is executive director of Urban Renaissance Institute and Consumer PolicyInstitute, divisions of Toronto-based Energy Probe ResearchFoundation. www.urban.probeinternational.org

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Let every roof bloom

Lawrence Solomon
National Post
November 6, 2004

Sod atop a building shields it from cold in winter, from heat in summer, and from sound year round. It makes buildings more hospitable for those who live or work within them. Roof vegetation also makes cities more hospitable for the general population: It cleans air of dust and rainwater of heavy metals, reduces smog, ground-level ozone and other pollutants, and moderates the “heat island effect” that raises city temperatures above that of the surrounding countryside.

For these and other reasons, dozens of cities in Europe and a handful in North America have become green-roof friendly. What started as a fringe environmental movement in Germany in the 1960s has grown to achieve mainstream acceptance. The Gap’s new headquarters in San Bruno, Calif., and Ford’s in Irvine, Calif., both use green roofs to improve acoustics and save resources, and many North American governments fund demonstration projects. The latest convert – Canada’s new Environment Minister, Stephane Dion – may well be right in saying last week, “This will be the future in 10, 20 years from now. You will see that everywhere.”

Green roofs may not bloom everywhere for long, however, under the approach of Mr. Dion and other government backers. Most green roofs are net money losers, even after counting savings for their owners in heating and air conditioning costs, and in lowered maintenance costs. To make up the shortfall, governments provide subsidies and other preferences, some of them sensible. For example, real estate developers must often provide a city with free parkland to win permission to proceed with a project. In lieu of green space at ground level, politicians have begun to accept green space above.

But politicians can be fickle, and preferences granted today can be withdrawn tomorrow, when green roofs are supplanted by another trendy technology. To make the future of green roofs safe as houses, they would need to be financially self-sufficient, by generating revenue. In many large cities, this already happens: Entrepreneurs are turning a profit from their rooftops, often surreptitiously and without need of government programs, through niche agricultural operations that capitalize on niche urban markets.

Many downtown restaurants tend their own rooftop gardens to obtain the freshly picked herbs and vegetables that their specialty dishes require. Toronto’s Royal York Hotel has one of North America’s most extensive open-air rooftop garden, growing enough organic parsley, sage, tarragon, basil, peppermint, spearmint, chives, marjoram and hot peppers to satisfy its restaurants’ 100 chefs from July to September. Speaking for chefs everywhere, John Cordeaux, the hotel’s executive chef, said “Everyone’s dream in any kitchen is to have their own herb garden [because] as soon as something’s cut, it will start to lose its flavour.”

Apprentice chefs pick herbs for immediate use and, between meals, kitchen staff tend the garden, which also grows vegetables such as runner beans and lemon thyme. Being 14 stories up has growing advantages, too. The taller downtown office towers provide shelter from the wind, and some insects and other pests don’t find their way to the roof (“There are no deer here,” the hotel quips), aiding the garden to be organic, a strong selling point in upscale markets.

The Royal York’s rooftop operation is legal – but just. Toronto’s zoning laws, like those in most cities, generally outlaw commercial agricultural activities within city boundaries. Because the Royal York’s agricultural output is peripheral to its restaurant and hotel business, and because it doesn’t sell its produce to other merchants, the city doesn’t enforce its prohibition. But many restaurants don’t have roof space at their disposal, or the staffing flexibility required to economically tend a garden. Urban farmers that opernly tried to set up commercial rooftop farms to service the city’s many tony restaurants, fine grocers, and chi-chi caterers would quickly be put out of business.

Remove these prohibitions and rooftop farms become financially viable without need of government subsidies. They would become a common feature within cities, alleviating the immense demand that now exists for urban gardens. With this new industry would come new jobs, mostly in small operations, many of them providing an important source of income for retirees, home workers, and others who don’t have 9 to 5 jobs. As green roofs became rooted in urban life, food freshness, food quality, and food variety would grow.

Green roofs would provide another quality-of-life amenity, too. Ever since King Nebuchadnezzar decided to please his queen by building the Hanging Gardens of Babylon – one of the Seven Wonders of the Ancient World – atop a large brick building south of present-day Baghdad, roof gardens have been planted in the human imagination. Roman architecture featured hanging gardens and rooftop vegetation, as did the city of Genoa during the Renaissance. In 17th century Russia and 18th century France, many constructed vertical gardens for their beauty. More recently, two of the greatest architects of the 20th century, Frank Lloyd Wright and Le Corbusier, extolled rooftop vegetation. This timeless vision has never been closer.

Lawrence Solomon is executive director of Urban Renaissance Institute and Consumer Policy Institute, divisions of Toronto-based Energy Probe Research Foundation.; www.Urban.probeinternational.org; Next week: Urban agriculture’s immense potential.

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