Lufa Farms Inc. has opened its first rooftop greenhouse farm atop a shopping centre, bringing 127,000 square feet of urban agriculture space to Montreal's Ahuntsic borough.

The greenhouse, located on the roof of the Marché Central Walmart and Decathlon building, is Montreal-based Lufa Farms’ fifth rooftop greenhouse farm.

It is also the company’s most advanced, according to Callie Giaccone, Lufa Farms’ public relations outreach specialist, who told Sustainable Biz Canada it features technology that optimizes crop growth and energy efficiency.

“This one we really feel is special in the sense that there’s Walmarts everywhere and there’s shopping centres everywhere. Being able to show proof we can build on top of Walmart makes it a lot more scalable and replicable,” she said.

Lufa Farms is an urban agriculture company with over 500,000 square feet of growing space. Its farms are located on the roofs or interiors of commercial and industrial buildings in Quebec, mostly in Montreal. Depending on the season, Lufa Farms harvests 200,000 items per week, including tomatoes, cucumbers, peppers, eggplants, beans, lettuce and herbs.

Building the Marché Central rooftop greenhouse

While the Marché Central mall greenhouse is not Lufa Farms’ biggest, it will be its most efficient, Giaccone said.

Lufa Farms started construction in 2023, finishing in mid-February 2024 after six to seven months of work by FDA Construction.

Plants are grown hydroponically with the assistance of approximately 20 staff members. Customers can purchase vegetables from Lufa Farms’ online marketplace, and have it delivered or picked up in over 350 partner locations in Quebec.

The Ultra-Clima air filter system and high-intensity LED lights will boost productivity by up to 40 per cent compared to other greenhouses of similar sizes, she added.

Energy efficiency will be supported with double-walled insulated glass to minimize heat loss and a diffused glass roof to distribute heat evenly.

Its hydroponic system will reuse the water supply and recirculate captured rainwater and snowmelt.

To reduce soil use, the cucumbers will be planted in a mix of fibres – half coconut husk chips and half coconut fibres stripped from the husk, while peppers will be grown in coconut husk chips.

Synthetic pesticides will be barred from the greenhouse. Rather, Lufa Farms will use natural pest control by introducing predatory insects such as praying mantises and wasps.

An additional benefit is offsetting the need for more agricultural land, a contributor to habitat destruction, biodiversity loss, decreased air quality and climate change. The urban farms also minimize transportation emissions as the produce is grown in the city in which it will be consumed.

The example Lufa Farms is setting shows urban agriculture is scalable and possible anywhere, even on the roof of big retailers, Giaccone said: “You can have a greenhouse on a Walmart. Why not have a greenhouse on every Walmart?”

Montreal’s urban agriculture ambition

Montreal plans to be a trailblazer in urban agriculture as outlined in its Urban Agriculture Strategy, part of its 2020 to 2030 climate plan. It involves increasing awareness about the concept, supporting production in the city’s limits, and improving the management and governance framework for urban agriculture.

The Ahuntsic borough is already home to another urban agriculture innovation: Quebec’s first urban fish farm. Giaccone described it as an “amazing borough that really values sustainable urban agriculture,” and Lufa Farms received support from the community for its latest project.

The Montreal borough of Saint-Laurent is home to Lufa Farms’ largest facility, a 1.6-million-square-foot indoor farm at a former Sears distribution centre, part of that neighbourhood’s plan for urban agriculture.

Lufa also has four other rooftop farms:

• a 31,000-square-foot rooftop greenhouse in Ahunstic;
• a 43,000-square-foot farm in Laval;
• a 63,000-square-foot farm in the Anjou borough of Montreal; and
• a 163,800-square-foot facility in Ville Saint-Laurent.