Like many cities across North America, Montreal has problems with localized heat islands during the summer, raising the temperature significantly compared with its surroundings. This effect is due to the density of buildings and road network, and not enough green space to absorb the sun’s heat. In addition, with changing and somewhat unpredictable weather conditions due to climate change, an increasing number of cities are beginning to experiment with different forms of urban agriculture. One of the projects in Montreal is a partnership between the Montreal convention centre (le Palais des Congrès de Montréal), the department of urban agricultural research from the university of Quebec at Montreal (AU/LAB at UQAM), Miel Montreal, and La Ligne Verte. This is a true collaborative project to learn what is possible regarding growing food within the confines of a rooftop. The project aims to fulfill several objectives:
- Reduce heat island effect for the neighbouring area;
- Absorb stormwater;
- Produce plants and vegetables for a variety of uses;
- Preserve heirloom seeds from some rarer varieties of plants;
- Demonstrate Montreal’s efforts to become a resilient city in the face of changing weather patterns;
- Provide a “lab” like setting to develop new vertical farming techniques.
There are three distinct sections of the project:
- CULTI-VERT (by La Ligne Verte) was responsible for growing vegetables, medicinal herbs and edible flowers in about 450 containers. The harvest includes a variety of fresh vegetables such as lettuces, tomatoes, peppers, squash, beans, edible flowers, herbs, squash, cucumbers, zucchini, eggplant, swiss chard and more. The project covered 5770 square feet of space with an average annual harvest of between 650-1000 kg of produce. Because the roof provides a microclimate due to its relatively enclosed space, the growing season is longer than average. Planting starts in mid-April and will end around mid-November.
- PROJET VERTical was a new program this year – occupying 6000 square feet of space and 5000 square feet vertically, the panels were used to grow a variety of herbs, lettuces, and strawberries. Metal frames hold fabric panels which grew 10 plants per panel. Water dripped onto felt fabric panels which absorbed the water. Excess water was collected in a drip tray at the bottom and fed back into a purification system and stored in a large cistern. The water was recirculated to feed the panels again. The only water that was lost was due to evaporation and slight spillage from the drip tray. Ideally, the water will be 100% rainwater, avoiding the use of the city’s water supply system. Next year they will add an additional 5-10 plants per panel. Both sides can be used, however, taking the sun pattern into account will maximize growth potential. It is significantly cheaper to grow vertically than horizontally.
- Pollination: Many of the plants grown here require pollination to successfully grow fruit or vegetables. Miel Montreal provided four bee hives to the project. The hives themselves produce between 50-80 kg of honey each year. This year was particularly dry in August, so the end amount of honey produced was around 45 kg (the bees will eat it themselves if they can’t find food outside the hive). This honey is complex in taste due to the multiple varieties of vegetables and fruit the bees are visiting on the roof. Because it is an organic garden, the honey is also free from pesticide residue.
Capital Catering uses the produce grown on the roof for its catering at the convention centre. The chefs arrive on the rooftop and choose the ingredients they need for some of the dishes. The rooftop garden also provides some of its harvest to Osco, the restaurant at the Intercontinental. In addition, Capital Catering shares the harvest with Maison du Père, a non-profit organization that helps homeless men by providing them with food, shelter and skills training.
This project is still in the experimentation phase, but the intention is to demonstrate that building rooftops can provide valuable growing space for some fruits and vegetables. The goal is to encourage local buildings with large enough roofs to use their resources in a similar fashion with all the benefits accrued from growing local, fresh produce while helping to alleviate heat island effect and absorb excess stormwater.