Urban food production is appealing for many reasons, but not all approaches are "sustainable" in the sense of being practical over the longer term. Now two pioneering projects developed outside the landscape industry show what can be achieved, and where the challenges lie.
Situated in a disused commercial building in Dalston, north-east London, FARM:shop is a demonstration urban farm by Something & Son, which describes itself as an eco-social design practice.
"I was interested in the interaction of food, cities and nature," says one of the youngish three-strong team, engineering graduate Paul Smyth. "How can we grow more efficiently and sustainably? This aims to come up with come answers."
The previously empty two-storey building was let to the team last summer on a five-year lease from London Borough of Hackney as part of its Art in Empty Spaces initiative. Centrepiece of the project is the cafe, where customers are surrounded by hydroponically grown vegetables and herbs and, more strikingly, tanks of large tilapia fish.
The two are intimately connected, explains Smyth. "The nitrate-rich waste water from the fish is recycled to the plants. We want the water to take a long journey through the plants to reduce the nitrates to a minimum before it's returned to the fish."
Tilapia have several advantages for such a system. They shoal in tight densities, tolerate a range of different water conditions and grow quickly, meaning they can be harvested in six months. There is also a ready market, especially in Asian cuisines, for its "chicken-like" flesh.
Above them grow herbs such as mint and camomile, used in herbal teas sold in the cafe, as well as leafy vegetables such as pak choi - all raised from seed. The hydroponic system, designed and installed with help from Aquaponics UK, is a "fairly standard" polystyrene-based floating raft format, overlit with daylight-equivalent lighting, Smyth explains.
In the hall upstairs, green wall formats are being trialled. "We are looking at food plants that are good low-light crops such as wild garlic and ostrich fern," says Smyth. The fern's immature fronds, called fiddleheads, are edible, but he adds: "So far the results have been mixed."
In an adjacent room, several kilos of tomatoes were grown over winter under more intense lighting, some of which were turned into chutney, to be sold through the cafe. This area has since been given over to high-value herbs and spices such as kaffir lime.
"We use a lot of energy so you have to grow out-of-season crops that are competing against imports," Smyth explains, adding that lower lighting regimes and even LEDs are being trialled in a bid to cut this. Solar panels are being considered for the roof, but given their long payback time, "we need to know about the long-term future of the site", he says.
"Another of the challenges is bugs. We had aphids over winter, and with no natural predators they can spread very quickly, so we introduced some from an integrated pest management supplier."
In a meeting room, also upstairs, basil is grown in a nutrient film technique system that zigzags down the walls. This has already yielded several litres of pesto, again sold in the cafe.
"I would like to see something like this on a warehouse scale that would help meet demand locally, especially for things that taste best fresh," says Smyth.
In the yard outside, a polytunnel has been constructed, its frame made with surplus wood from the Aquatic Centre at the nearby London 2012 Olympic site. It is hoped that a small pond will sustain a population of pest-eating frogs.
Smyth and his team even have plans to introduce pigs, lent from a partner farm in Hertfordshire. But he cautions: "The waste is difficult to deal with. You can feed them kitchen scraps but you can't then sell the meat."
Building on expertise
However, four chickens on the roof space are already providing fresh free-range eggs for sale and for use in cakes in the cafe. Other projects include production of kefir, a traditional eastern European beverage of fermented milk, which is brewed in jars in the hallway, to be sold at the bar. Growing shiitake and oyster mushrooms in trays of moist sawdust will be next. "We aim to show how easily it can be done," says Smyth.
"We have some expertise but the rest is trial and error. It's not a quick project - you have to stick at it. It's not chiefly about the technology, it's more about reconnecting people with food production. The thing we are most happy about is the community side. We engage with people though the cafe and through offering it as an events venue. This is a very mixed area and people have all kinds of food stories."
On the economics of the project, he says: "No one has given us money, but they have given us stuff and time. We are non-profit - everything recirculates - but FARM:shop still stacks up as a business. We focus on high-value crops and the food production covers its own costs.
"But a bigger site would give you economies of scale. That's where our focus is now - we are looking for partners. We have had a lot of enquiries and have been to visit a few places. We are committed to replicating this and are starting to imagine where else it could be done."
THE SKY'S THE LIMIT
Supermarkets have a reputation for clocking up high food miles on their sales lines. But at the Budgens store in Crouch End, north London, herbs and vegetables come from no further afield than its roof.
Food From the Sky is the brainchild of Azul-Valerie Thome and supermarket manager Andrew Thornton. Its sustainability credentials are impeccable - the crops are grown in recycling crates filled with green waste provided by the local council. It scooped the Community Award at the inaugural People & the Environment Achievement Awards in March.
"It came about over a coffee with Andrew in November 2009 - we had a shared vision of growing food on roofs, but didn't know where to start," says Thome. "We went through a few months sorting out the legal and structural issues."
By May last year the two had enough money to hire a crane which took 10 tonnes of green waste compost and 300 recycling boxes on to the roof. "The borough gives away the compost - we only paid for delivery," she says. "We bought some seeding compost, though," she adds.
The re-use ethos continues to using toilet rolls and egg boxes as pots for seedlings. Thome adds: "We follow the biodynamic calendar and employ permacultural principles - it gives a higher yield."
She recruited 20 volunteers through local groups. "People have different reasons to be involved," she says. "Some are interested in sustainability, some are considering making a living out of it, some just want to bring life back to the city."
One volunteer, Jayne, a part-time lecturer, says: "I am being made redundant, but have an RHS certificate and am spending more time looking after other people's gardens. It's nice to do something different and I love being outdoors."
Another, Peter, divides his time between organic gardening and work as a film and television extra. He says allowances have to be made when working with green waste as a growing medium. "It needs mixing and a bit of time to settle. There is woody stuff to take out and even random things like knives and forks."
The project yielded its first saleable crop in July last year and now includes leaf salads, tomatoes, herbs, kale and edible flowers. "They go on sale on Friday and by Saturday they are gone," says Thome.
Access has since been improved with an external scaffold staircase. The project has also looked at extending the range and seasonality of crops by putting up a polytunnel. "But the plastic flaps and tears in the wind and the residents complained," says Thome. "Really you would have to concrete in the foundations."
Community involvement has been boosted through events such as Climate Week in March when local people were invited up to pick their own, with talks and games for children. "Part of the project is its relationship with the community," says Thome. "The response has been amazing, but there are tensions. Some of the people who overlook it aren't happy."