Rooftop City Farming
"ome urban farmers and their farms are well disguised. Eli Zabar is a Manhattan baker, retailer and restaurateur. Up on the roof of a three-story brick complex on 91st St., under the eye of neighboring apartment buildings, his big commercial rooftop greenhouses cover raised beds pumping out herbs, salad greens, radishes and tomatoes. A compost grinder helps convert bakery and deli waste into compost. Exhaust pipes from the ovens downstairs keep the greenhouses at the precise temperatures that work for growing tomatoes in the winter.
Restaurants all over North America are doing the same thing--growing what they can on-site, either in a ground-level garden, or, like the restaurant at the Fairmont Waterfront Hotel in Vancouver, on an upper-level courtyard. At the Uncommon Ground restaurant in Chicago, volunteers hauled six tons of topsoil up to planter boxes on a 2,500-square foot rooftop garden.
Converting a roof to a garden isn't easy. The weight of the soil and the constant human traffic up to a rooftop requires extra support, which can be expensive. One of Uncommon Ground's owners estimates he spent $150,000 on construction. "We resupported the entire building. We dug down five feet and put in all new posts and beams. That was all to support what we wanted to do on the roof.... My structural engineer said we could probably land the presidential helicopter on the roof."4 Uncommon Ground's roof also features a pair of beehives that produce 40-50 pounds of honey for the restaurant.
Brooklyn's Grange Farm has gone one better. Boasting the world's biggest rooftop farm--on the Standard Motor Products building in Long Island City--its one acre of garden required 600 tons of soil to be hauled up six stories in a 91-year-old building. The Long Island Business Development Association was so impressed, it presented Gwen Schantz and the Grange Farm with its 2010 Green Business Award.
Or would you like rice with that? Mori Building, developer of Roppongi Hills in Tokyo, is using rooftop gardens to create "vertical garden cities" to add green space to a depressed area and dampen its intense urban heat island. The company's Keyakizaka complex rooftop boasts a seventh-floor rice paddy--yes, rice paddy--and vegetable plot. The paddy is small (155 square feet) and largely symbolic, but still capable of producing 135 pounds of rice, with elementary school students doing the planting and harvesting under the instruction of rice farmers.
There's lots of rooftop space potentially available. By one estimate, the 4.8 million commercial buildings in the United States have about 1,400 square miles of roof, most of it nearly flat. That's an area larger than Rhode Island. Not all of it is useful for rooftop gardening. Aside from the obvious structural loading issues, acceptable access to the roof is critical. In many multi-family residential or commercial buildings, occupants may not want urban farmers with wheelbarrows of compost and muddy tools traipsing through a public lobby. But even leaving out the roofs that are shaded, inaccessible, or structurally unable to support rooftop activity, that's a lot of growing space." (http://www.realitysandwich.com/urban_suburban_growing_food)
- Book: The Urban Food Revolution. Peter Ladner.