As our modern society treads ever forward into the future – we build.
Houses, office buildings, shopping malls and factories. The city grows, complicates and defies prediction. A by-product of building is the creation of a lot of unused vertical surfaces. These vertical surfaces can be used as support for food, waste or ornamental systems.
In dense forests plants compete for nutrients, water and sunlight. Epiphytes are those plants that “put the need for light” so to speak, above other needs. They find ways to germinate high in the canopy where light is abundant and cope with the problems of obtaining water and nutrients after they have secured their place in the sun.
It is possible, even constructive to think of our cities as jungles, where light, moisture and heat are available but in short supply. If we are to turn our domesticated plants into “urban epiphytes” we must provide them with purchase, nutrients and water. In this way, the photons coming from the sun and bouncing off our walls are channeled to make plant tissue instead of generating light and heat.
But why should we grow plants at all? The food system seems stable and the supermarkets seem to be always full. But there are several advantages to growing plants ourselves, namely: food, health, habitat, education and relaxation. We do not understand our own food system well enough to be able to predict shortages or even price spikes. That’s why having an urban backup system for food production is very comforting.
It is worthwhile to stop here and think about the differences between urban and industrial agriculture because they are fundamentally different from one another.
Industrial agriculture applies strict protocols to monocultures planted on huge expanses of land of uniform conditions.
Scale plays a role here in that as a simpler and simpler task is performed more and more times it is performed more efficiently. Also, machines are built to tirelessly carry out these ultra simplified tasks driving efficiency higher.
Urban agriculture tinkers with new protocols to polycultures planted on many small plots available in the city that differ from each other in conditions.
In efficiency, urban agriculture cannot compete with industrial agriculture. Urban agriculture is limited by the city to small plots of varying geometries. Industrial agriculture, on the other hand, is conducted on flat, deforested rolling expanses that occupy 1/3 of the earth’s land. And if that difference does not suffice, the diversity of different products and the minute yields of each product produced by urban agriculture diminish the incentive to devise machines to assist. So, with its inherently small scale and inherent non-mechanization urban agriculture can never come close to the quantity and thus to the price of industrial agriculture. A head of lettuce grown in the city will always cost more than one grown in the field because relatively more work went into it. The machine assisted field farmer has no will and no need to manicure every head of lettuce, whereas the urban farmer has no choice as she is planting, weeding watering and harvesting by hand.
When recognizing that the geometry of the city itself impedes urban agriculture’s capability to compete in efficiency with its field dwelling counterpart it is useful to recall the aforementioned advantages of growing plants ourselves – without which urban agriculture would seem like a useless undertaking.
However, in the very same way that when we build a modern building we pour the concrete that is the skeleton and then “finish” the building by adding a very long list of details that cater to our smaller needs. Diverse, low yield urban agriculture seasons up the monotonous bulk that is produced in the field. Just as it would be very difficult to use a building’s bare skeleton by itself - before doors windows, plumbing and furniture were installed – similarly the food from the field provides the bulk calories onto which taste, reason and ritual are fitted. So with this metaphor in mind we understand that field plants give us calories and city plants can potentially give us taste. But we also mentioned habitat, education and relaxation. Why are they important? And how does the growing of plants in the city provide them?
We must divert our mind’s eye to hover over the fields of wheat and corn being harvested mechanically. Row upon row of plant similar in height breadth and timing to all their other brethren in the field. The picture we see is one of repetition and homogeneity. The field farmer must take land and ascertain that everywhere on the land will be equally warm, equally salty, equally windy and equally moist so as to provide all his very similar seeds with very similar conditions so that they may develop into very similar plants so that they can be similarly harvested by one machine at the season’s end.
Fortunately for our story - the geometry of the city supports conditions that are anything but homogeneous. The city’s jutting landscape creates microclimates that change drastically over the space of a few yards. Here we have densely packaged diversity. Diversity of moisture conditions, light availability, air currents and temperature. Every step is a new world unto its own and can potentially provide habitat for a different organism. So if we open our minds and to the natural world the city can become a "Noah's Ark" of sorts - preserving biodiversity in its myriad folds and structures.