Garden City Part II – Kitchen Gardening
Once we examine the city as a whole and assess space for growing food, how do we prioritize our growing energy? It seems to me that space where water is available and where people visit daily or regularly would be ideal. Soil, of course, is not such a challenge. San Francisco still generates somewhere around 3,000,000 pounds of organic waste daily that still end up in the landfill (we do compost some 500 – 600 tons of organics a day as well). Therefore soil transformation – the creation of a growing medium would not be a current barrier to growth, all we need to do is take some of our waste stream, combine it appropriately and add water.
In consideration of those criteria, I would advocate for backyards as the primary place to focus our food production. We’ve begun to study the San Francisco landscape using GIS and satellite maps to attempt to inventory the backyards available in SF. We’ve arrived at a preliminary figure of 5,500 acres of land (239,900,000 sq. ft.) of area uncovered by structures was found within districts zoned for residential use. This area includes backyards, side yard and front yards, as well as vacant lots. Given the area of San Francisco is approximately 29,900 acres (1,300,000,000 square feet), roughly 18% of the City falls within areas zoned for residential uses could potentially be put into food production.
Well, how much food could we grow in our backyards? The highest yields we have seen are in Southern California at the Path to Freedom home in Pasadena where they yield over 7,000 pounds of food on 1/10th of an acre in production. Of course, they have a favorable year-round growing climate and, they use an abundance of water and 4 adults provide day-to-day energy input in order to achieve those yields. If we use that figure we would find 70,000 pounds per acre. If we multiply that by ceiling backyard acreage of 5,500, we would find 385,000,000 lbs of food a year grown in our San Francisco backyards!
In terms of utilizing backyards to meet our needs for full human nutrition we encounter both challenges and opportunties. The primary challenge comes from the predominant dietary preferences. The carbohydrates we get from grains, whether oats, wheat, rice or other likely require larger spaces than we are likely to find in a dense city like San Francisco to achieve yields supporting most diets. It might be valuable to note that all grains can be cultivated on a backyard scale, incluing phenomenal reported yields from quinoa and amaranth (both of which would do really well on the eastern half of SF). That said, grains, plus proteins from field pulse agriculture (think black beans, field peas, etc.), proteins and fats from ruminant meat and fat in the form of oils (grape seed, sunflower, olive oil etc.) are all unlikely to be found to be appropriate for small scale, intensive, dense urban food production. All that said, we need not totally discount the value of small livestock (guinea fowl, chickens, ducks, pigeons, rabbits), small scale grains and super successful bean crops (e.g., scarlet runner beans) in terms of their contribution to human nutrition from our gardens.
However it seems most appropriate, here in San Francisco, to mainly focus our kitchen garden energy on high/dense vitamin and mineral content fruits and veggies in addition to appropriate carbohydrate-rich (hopefully protein rich, too) root crops. I suspect if we focused solely on fruits and veggies we may be able to meet a large percentage of our vitamin and mineral needs if we cycle all our appropriate wastes back into our intensive urban food gardens. A broader discussion would be needed to design a regional food system that includes extensive holistic ruminant (and rotational allies) grazing, oils production and no-till grain and pulse field agriculture.
Probably the primary advantage to focusing on homescale kitchen gardens as a priority is access to water and, importantly, the potential to reuse household water (i.e., greywater) in our landscapes. There is a massive function stack to creating a richer topsoil in our urban gardens that becomes the discharge point and cleanser for 70-80% of our household water. On a large scale, greywater implementations could have an enourmous impact on slowing the depreciation of our largest municipal linear asset – our combined stormwater/sewer system.
Directing our graywater into appropriately design kitchen gardens with fruit trees and perennial vegetable systems adjacent to mulch basins ready to receive fortified water on a daily basis could mean incredible enhanced yeilds (even just biomass for mulch and energy if not food) in our gardens. Even the additional irrigation reqiured for kitchen gardens would be a more valuable use of water than for lawns, purely ornamental vegetation or, importantly, more valuable than using that water in industrial agriculture row crop systems in dry California valleys (the largest users of fresh water in California). Of course, most, if not all, households, with a backyard in California, have a metered mains water supply that could be designed to feed inline drip irrigation systems and or handwatering regimes or olla filling systems.
Another funciton stack resulting from a proliferation of kitchen gardens in and around homes in San Francisco is the opportunity to capture even more of our organics waste stream and, for those households now feeding the wonderful, yet energy intensive, green bin program, we could direct a percentage of our food scraps and paper carbon into vermicompost sytems and other compost piles in our gardens which would be necessary to maintain and enhance fertility which in the long run could lead to ever increasing kitchen garden yields, greater biodiversity, cleaner air, cleaner water, less stormwater/sewer system overflows and more nutrition dense vegetables supporting healthier people reducing health care costs, improving mental acuity and inner peace, resulting in outer peace and greater reverence for life in general 🙂 Oh the power of the worm!
Sometimes kitchen gardens might be appropriate on privately owned land that is not necissarily a backyard. We have indentified hundreds of vacant lots (commercial and residential) that might be appropriate for kitchen gardening at least for an interim period before such lots get developed. The San Francisco planning deprtment has just piloted a process, the green development agreement, to help put vacant spaces into productive use, prioritizing urban agriculture, in the interim before develpoment that helps the developer exend entitlements and protects them which may enable interim use.
Of course not all of us live in a building with a backyard and not all of us have the strength, energy and ability to garden. The concept of gardening in someone else’s backyard is not without precendent. Indeed San Francisco has a number of programatic support initiatives from various NGO’s, Kitchen Garden SF, SF Victory Gardens and Yards to Gardens to name a few. Brooke Budner, of Little City Gardens, experienced first-hand the possibilities inherent in our untapped backyards when, in 2007, she noticed a vacant, underutilized backyard adjacent to the apartment building she was living in. She asked a neighbor for the phone number of the landloard and after one conversation with the owner, she had a code to enter through the garage and within 48 hours one of San Francisco’s most impressive gardens was being cultivated. The landlord was receiving free, high quality landscape improvements (property value increasing) and all the neighbors enjoyed the view of food growing.
That raises another side effect of backyard gardens – surplus and the neighbor effect. It is a common backyard garden experience in San Francisco to see a bundle of chard cross the fence or a basket of apples or a bunch of arugula. It is also common to see neigbors begin to develop food gardens in their yards with the abundance of an adjacent garden occupying their line of sight. Perhaps, in time, we will see a movement towards increased de-fence spending here in San Francisco and accorss America – where we spend some energy taking down de fences!
If you have or knowof a backyard that you would like to see transformed into a productive food garden, please visit the Kitchen Garden SF website and register a garden. We are working on coordinating the effort for us all to enjoy the many benefits of a garden city full of kitchen gardens.