Urban land is often expensive; land owners are loath to tie it up long-term with things like urban farms, when what they really want to plant are condos. It's the same with rooftops. Deena DelZotto and Rachel Kimel, founders of the Bowery Project, had an idea:
Passing through downtown Toronto, noticing several lots which had been vacant for years, they asked themselves, why can’t we grow food there? There was no good answer why not. The seed was planted and the journey began.
Their clever twist is to build their gardens in milk crates, sort of a prefab urban farm. They claim that a "farm of up to 5000 crates can be disassembled and relocated within 24 hours. This mobility allows for an easy change of location when the land must be claimed for it’s subsequent use – such as development, remediation or sale." A lot of urban land is contaminated, and this is a good way to keep the farm away from the lead and oil and other toxic stuff found near the surface. It is a good way to create opportunities for urban agriculture.
Their first installation was at the Green Living Show in Toronto, set up in the Urban Agriculture Pavilion. This only runs for three days, but theirs will be one of the easier booths to disassemble.
The milk crates are lined with a filter cloth that has been sewn into the shape of the box and filled with soil. This is a wonderful idea, particularly in cities like Toronto where vacant land doesn't sit around for very long. More at the Bowery Project.