‘Produce local. Eat local’ is the motto of modern urban farming, but growing organic vegetables on a big scale is challenging. In 2017, Canadian authorities required a grocery store in Montreal to install a green roof. IGA Extra Famille Duchemin in the St-Laurent borough decided to follow the new urban farming policy. It set up a vegetable farm on its sprawling 25,000-square-foot roof. They now grow certified organic produce on the rooftop, which is harvested and sold to the store’s customers.
Store owner Richard Duchemin says that he wanted to set an example for other grocery stores by setting up a garden on the roof.
“People are very interested in buying local… There’s nothing more local than this… Why don’t supermarkets plant vegetables on their roofs? Some restaurants have little boxes where they grow herbs… We pushed it further because we know we’re able to sell what we produce here,” he told the Montreal Gazette. The rooftop farm grows 30 varieties of produce, including eggplants, tomatoes, kale, radish, and basil.
However, setting up the rooftop farm came with its own unique set of challenges. In contrast to a regular farm, the rooftop soil is much shallower, limiting what can be grown. Fertilizing the soil is also a problem. Since the rooftop is exposed to external conditions like wind, heat, and other natural elements, equipment had to be installed to protect and sustain the plants’ growth.
Maintaining the farm is also costly. However, the store sells the produce at the same rates as other organic produce, generating decent returns. The rooftop farm provides an extra layer of insulation, lowering the store’s electrical consumption. It also plays a critical part in its LEED Gold certification, one of the highest standards of a ‘green’ building.
The farm uses water recycled from the store’s dehumidifying system, which would have been wasted otherwise. It also provides a habitat for birds and insects like bees. Several hives on the roof house the bees. The store plants special flowers that repel insects to keep out unwanted bugs. The store plans to sell these flowers in the future.
Largest rooftop farms
There are other larger rooftop farms in the world, such as the one setup by Agripolis at the Paris Expo Porte de Versailles in France. It covers an area of 140,000 square feet, which is roughly the size of two soccer fields.
The plants are grown in columns using rainwater and nutrient solutions. No soil is used in the cultivating process. Also, no pesticides or chemicals are used, ensuring it’s as healthy as possible.
The biggest rooftop farm in the world is a Lufa farm in Montreal located atop a warehouse that covers approx. 160,000 square feet. Around 100 varieties of vegetables are grown all year round at the farm, including celery, cucumber, lettuce, sprouts, and zucchini.
“We are now able to feed almost two percent of Montreal with our greenhouses and our partner farms… The advantage of being on a roof is that you recover a lot of energy from the bottom of the building… We also put to use spaces that were until now completely unused,” company spokesman Thibault Sorret told AFP.