With 100 tons of soil on top of a five-story car auction hall in central Copenhagen, the community-based ØsterGro project has created a real urban rooftop farm, which will not only have plenty of organic vegetables, but also bees and chickens to produce honey and eggs for the association’s members. But how is it possible to construct a large farm in the middle of Copenhagen and will it be safe to eat the vegetables?

“The idea is to have a real farm, centrally located in the city, where people get their vegetables and can keep close to what's going on. From week to week, people can see how the lettuce grows until they finally get it home, “ says Sofie Brincker from the initiative group.

ØsterGro started in 2013 when a group of young people decided they wanted to start an urban farm on their own to connect urban dwellers with sustainable farming. The inspiration came from New York where the large rooftop farm Brooklyn Grange is one of many examples of urban gardening that is now sweeping the big cities. The group searched Copenhagen for an appropriate spot and quickly located an attractive rooftop in the Østerbro neighbourhood of Copenhagen. The site has many obvious advantages such as being fenced-off, having access to water and sewage, and is freely provided by the owner of the building.

In April 2014, more than 100 tons of soil was lifted by a crane and loaded on top of the building. For a whole weekend, 70-100 volunteers helped to shovel soil into neat rows, and then they could go ahead with planting and sowing the 600 square meter urban farmland.

By the end of its first growth season, the farm has already delivered plenty of tomatoes, kale, carrots, lettuce, beet, beans, chillies, herbs and flowers; enough to support the 16 members of the rooftop farming community. More recently, the members have also been able to get eggs and honey with their weekly box of between 6 and 10 different vegetables.

Rooftop farmed tomatoes (click for larger image).

The ØsterGro rooftop farm is a Community Shared Agriculture (CSA) association where members pay 3,000 Danish kroner (400 euros) each year to receive locally-produced organic food in season. There are currently 16 members but 50 families are on the waiting list to join ØsterGro.

The farm is run by volunteers but it is the plan to hire a part-time urban farmer, as it is not economically viable to operate such a big project with volunteer labour alone. In addition to income from the vegetables, the ØsterGro team has plans to offer workshops, courses, tours and events. For example, ØsterGro hosted several evening events during the food festival, Copenhagen Cooking, where guests could come and eat an organic dinner prepared on site from fresh vegetables and served in the greenhouse up under the evening sky.

(click for larger image)

A concern that urban gardening is often met with is whether the food grown is safe to eat. However, researchers at Copenhagen University found in a study from 2012 that it is perfectly safe to eat vegetables grown in urban areas. They examined three different urban gardens in Copenhagen and found that vegetables grown in soil contaminated with relatively high levels of air pollutants and heavy metals, contained no more harmful substances than vegetables grown in uncontaminated soil. In fact, vegetables from ØsterGro and other urban gardens may be even more safe than conventional produce as they have not been sprayed with pesticides.

After its first season, the ØsterGro farm is now ready to shut down for the winter. Green manure and nitrogen-fixating plants, such as clover, beans and cress, have been sown, expecting to make the soil even richer for next year's growing season.