Stand by for aeroponics! Plastic columns with small cylindrical outlets, growing fruit, vegetables and flowers, their roots dangling inside the column in nothing but air. They get sunlight, they get watered, and that’s what makes plants grow. They don’t need earth. They certainly don’t need pesticides. And the water the plants don’t use is recycled.
Nature Urbaine began production on the roof of an exhibition centre in Paris, in 2020. It has 14,000 square metres producing 10 tonnes of aeroponic and hydroponic vegetables, flowers and fruit per season.
There are thousands of farms like this: Paris alone has more than 50. But Nature Urbaine, about one and a half times larger than the playing surface of a rugby field, is the biggest in Europe and the first in the world to net offset carbon.
Urban farms offer many benefits. They cut down on the cost and emissions produced by transport. They have an educational function and build communities: Nature Urbaine rents out 156 spots for local apartment dwellers to do their own cultivation.
The can reuse greywater and a building’s heat and improve insulation against noise and heat loss. Greenery in the city attracts more birds and insects, protects the roof from solar damage, improves air quality, reduces urban heat and helps prevent rainwater from flowing into overburdened stormwater drains.
And they’re a tourist attraction, which generates income. Nature Urbaine has a restaurant onsite and sells its produce to local residents and businesses.
The greening of Paris isn’t limited to reducing cars and growing veges on roofs. The city is adding 3000 hectares of farmland to the Greater Paris area, while AgroParisTech, an institute devoted to environmental sciences, is helping local farmers adapt to the climate crisis.
Christine Aubry, an urban agriculture expert at AgroParisTech, says, “We are still far from our target for agricultural space in Paris, but there’s a clear upward growth and it’s accelerating.”
Urban agriculture will never feed the world, or even the cities it’s a part of. A 2014 study in the Italian city of Bologna hopefully suggested rooftop farms could provide 77 per cent of the city’s food, but that result seems like an outlier. A 2018 report suggested around 10 per cent of the global demand for legumes, roots and tubers and vegetable crops could be sourced from all types of urban farming, including land on the edge of urban areas.
The rooftop option is still valuable, though, for food and for all the other reasons. Especially in cities where the rich-soiled hinterland has been swallowed up by housing – which is probably most of them.
In Auckland, the council has taken the lead. There have long been beehives on the roof of the town hall and last year the central city library established a new green roof. More than 2000 plants are growing there, although most are not edible. The city is ripe for more: let a hundred rooftop gardens bloom!
Simon Wilson is a senior writer covering politics, the climate crisis, transport, housing, urban design and social issues, with a focus on Auckland. He joined the Herald in 2018.
Design for Living appears most weeks in Canvas magazine.