Urban farming is "booming" worldwide but local factors determine the viability of such schemes, particularly at larger scales, Marie Dehaene, a consultant on many urban farming projects, told a seminar at Sival.
"There is a huge variety of formats and business models," she said, ranging from lowto hi-tech, under open air, in glasshouses or in fully controlled environments, coupled with rapid technological development. "There have also been changes in stakeholders, in the law, in building ownership and management that have encouraged people to do it," said Dehaene.
In France, "the momentum is strongest in Paris", thanks to public policy support, she explained. "I learn about a new start-up every week." Under its mayor Anne Hidalgo, the French capital aims to have 100ha of roofs and walls planted, with one-third devoted to fruit and vegetable growing, alongside green waste reuse and the creation of orchards and vegetable gardens in every school.
"Then there are the large-scale 'plant factories' in the US and the Far East," she said. "We haven't reached that stage here, but there is potential for it. Should it be about ecological and social goals or just production? Will they be in competition with conventional growers?"
The drivers to such developments have been particular to those countries, Dehaene told Horticulture Week. "In New York most fresh produce comes from California or Mexico. California is under environmental strain and there are concerns about traceability. In Singapore there is a drive for greater food self-sufficiency, while in Japan there has been concern about polluted land post-Fukushima. People lost trust in the quality of produce and some typically Japanese vegetables can't be imported. So in these places there has been a real reason to make it viable on a large scale. There are also such projects in France but there is a cultural difference too. Is having our food cultivated by robots something we dream of?"
Urban farming also throws up legal and regulatory issues, she added. "Is the operator a 'farmer'? This has tax implications and there is a whole legal framework that farmers have to abide by."
Examples - Urban farming systems
In North America, where the movement has already advanced in many directions, examples include:
- Canadian-headquartered Fairmont Hotels, which has a programme of vegetable and herb gardens at many of its hotels, which also have their own beehives. "Their aim isn't self-sufficiency, which isn't realistic, but to make a contribution," says Dehaene.
- Gotham Greens has four rooftop glasshouses in New York and Chicago totalling nearly 16,000sq m, including one in Brooklyn supplying a Whole Foods Market store underneath.
- The nearby Brooklyn Grange Farm has 6,000sq m of conventional open-air crop growing in soil because it is housed on an "extremely robust" commercial building able to support large volumes of earth. Produce is sold to local restaurants, which commit ahead of buying. "It has diverse uses - you can even do yoga or get married there - which helps it reach break-even point," Dehaene points out.
- UpGarden in Seattle is an award-winning 16,000sq m publicly accessible community rooftop garden on top of a multistorey car park. "If it can support cars it can support planting," says Dehaene. "There are many sites like this and this kind of project is picking up pace."
- Green Spirit Farm of New Buffalo, Michigan, houses year-round indoor vertical farming in a former plastics factory adjacent to a power plant that supplies it with cheap energy. "In rust belt areas like this, urban sites are free or comparable to farmland," says Dehaene.