While January 13 may seem rather late for my first post of 2012, the subject of this post will seem rather early in the year for the majority of my readers who are in the northern hemisphere. I’m leaving plenty of time to plan and scheme to make this happen…
A few years ago, I saw a church in North Minneapolis that had expanded its community garden to cover part of its parking lot. No, they didn’t tear up the parking lot and replace it with the garden, they just created a garden on top of the asphalt.
I don’t know why this was so surprising to me at the time — if relatively tall and healthy plants can grow in pots which have less than a foot of dirt on top of plastic, why not on at least a foot of dirt mounded in rows on top of asphalt? In any case, the fact that people were growing food on top of a parking lot demonstrates the popularity of community gardens, but also the dwindling amount of space for such gardens in densely populated areas. Community gardening is more than just a fun weekend activity. As the world becomes more populated and more urbanised, urban agriculture is being recognised as a important component of food security.
So far, the amount of available land seems to be the main constraint on the growth of urban agriculture. But the garden-on-asphalt suggests there may be a way around that.
Green Roofs are already growing in popularity for new construction projects. Community gardens are already popular on the ground. But as far as I know, these two concepts have not been merged on the scale I now propose:
The Idea: Gardens in the Sky!
Rather than suggest that we start installing rooftop gardens on new buildings, I believe there are already plenty of existing garden-ready surfaces in places where people already live. I would suggest that there are three criteria a surface must meet to be viable for rooftop gardening:
1. It must be flat. Sorry, Al Johnson’s Swedish Restaurant in Door County is not a suitable model
2. It must have a large, continuous surface area. If it is to be viable as anything more than a hobby garden for a few individuals, the surface needs to be large, and if it is to be functional, the area needs to be mostly continuous
3. It must be in a densely populated area. This isn’t necessary for the rooftop garden per se, but if it’s not in such an area, then it wouldn’t have much advantage over the conventional ground-level garden.
There are a few places that meet these criteria for sky gardens. The first that came to mind was the area in Loring Park near downtown Minneapolis where I lived several years ago. Here’s are screenshots from Google Street View and Bing’s Bird’s eye view of the street on which we used to live:
As you can see, these apartment buildings are the same height, probably because they were built around the same era in the early 1900s. They are all relatively close together, making it possible to join them with walkways to make an even larger continuous area. There are plenty of areas with this same characteristic (concentrated apartment buildings of almost uniform height) in older neighbourhoods in most American cities. For example, these rowhouses in Washington, DC would make a good candidate:
Another category of rooftop suitable for sky gardens is the mass-produced concrete apartment blocks that sprung up in every country the Soviets touched. What these buildings lack in style or charm, they more than make up for in sky garden-suitability! Once again, uniform height and close proximity would make it possible to link several buildings’ roofs together to make one continuously accesible surface.
Sky gardens in those parts of the former Soviet Union with heavy groundwater and soil contamination would have an extra advantage over ground-level agriculture.
So far I’ve been focusing on groups of buildings of uniform height that could be amalgamated into one large growing area. But, there’s one more category of building that rivals the Soviet apartment blocks in both architectural elegance and sky garden-readiness. These individual buildings are suitably massive by themselves, without any need to be adjoined to adjacent buildings. I’m talking, of course, about the big box stores.
Here are a few stats to consider: the average Super Target covers 174,000 square feet or 4 acres. The largest Wal-Mart (in Albany, NY) covers 260,000 square feet, or almost 6 acres! That’s plenty of room to grow anything. Heck, even I might be convinced to darken the doors of a Wal-Mart if I could buy the most local produce possible — grown directly above the place where it’s sold.
There might be some other surfaces that meet the criteria for sky gardening: public housing projects in the US? Certain airport terminals? I don’t know, maybe you can help me think of more.
I’m also aware that there might be some technical challenges to sky gardening that wouldn’t bedevil conventional green roofs. Maybe you can help me identify those and find a way around.