by CHANTAL MARTINEAU

For the country's second most populated city, Montreal is not exactly lacking for green space. We have an abundance of parks and squares, trees and grassy areas, pedestrian walks and more than 600 kilometres of bike paths. But that still leaves 80 per cent of the city covered with buildings and paved surfaces. One way to escape the urban jungle is to pack up and head for the hills. Another more feasible option is to create a private greenspace in your home. Or on top of it.

The flat-roof triplex, a quintessentially Montreal-esque dwelling found in dense pre-war neighbourhoods like the Plateau, is ideal for accommodating a green roof. And while aesthetic motives for replacing standard tar-and-gravel roofs with plants and flowers are obvious, environmental benefits might not be. Adding vegetation to the city's rooftops can improve air quality, reduce excess water runoff and regulate the interior temperature of a building, thus cutting energy consumption.

Joy of hydroponics

An extensive green roof comprises a six-inch (15-centimetre) soil base sown with robust plants and flowers. It's a lightweight option requiring little maintenance that can, over time, be more cost-effective than a conventional roof. The intensive variety uses more soil and is therefore heavier, but can be used as a fully operational roof garden where you can grow vegetables, host terrace parties and just sit around soaking up the sun while the metropolis buzzes below. A hanging garden, made up of planters scattered around the roof to provide shade, can also be enjoyed as a terrace.

Alternatives, a Montreal-based organization that promotes international development, is touting a lighter, simpler and cheaper way to create a hanging garden using hydroponics. It's an agricultural system familiar to most marijuana smokers that involves growing plants in water. Montreal roofs are generally built to hold 20 pounds per square foot. A soil-less technique eliminates the heaviest part of a garden - namely, the soil - and is relatively easy to set up using store-bought basins or recycled materials.

"If you do hydro right, you can get four times more productivity and use one-10th of the space [of a regular garden]," says Alex Hill, who heads up the Rooftop Gardens Initiative, among other environmental campaigns at Alternatives. His goal is not only to encourage Montrealers to get excited about roof gardening but to eventually export the concept to developing nations as a means of sustainable food production. Even here at home, he hopes to introduce roof gardens to low-income households as a means for families to grow their own produce, if only for a few months out of the year.

"I'm not going to fool anybody into thinking a family of five can feed themselves for the year," says Hill. "But they can produce food, healthy food... It's economical and a great way for kids to get active."

Beyond the community plot

Gardening has now beat out hockey and skiing as Canada's number one pastime. The luxury of a personal garden, which has traditionally been out of reach for most city dwellers, has become a possibility in recent years through communal gardens and community plots. But waiting lists to become members or claim a private plot are long, up to five years. For those who want to garden now, starting a roof garden can cost as little as $30.

Alternatives' own roof garden, in collaboration with Santropol Roulant atop the Université du Québec's Télé-Université (TelUQ) building, will be tended by a staff of volunteer gardeners. The produce harvested is donated to Santropol Roulant's Meals on Wheels program. Hill says volunteers are welcome to take home a sample of what they grow, especially in the case of vegetables indigenous to the Montreal region, which he hopes to incorporate into the garden next summer. After all, he adds, more variety in one's garden means more variety in the diet, which increases enjoyment and boosts the immune system.

"We wanted to make something ornamental and utilitarian," says garden coordinator Ismael Hautecoeur. "Good for the eyes and good for the stomach."

The garden will feature shrubs, climbing beans and edible flowers, such as pansies, carnations and calendula. The basins will be moveable depending on light and weather to keep the space as flexible as possible. Next year, there are plans to work with a nutritionist who would advise on what foods to grow specifically for Santropol. Once the garden begins to flourish, the public will be invited to visit.

Over the next three years, Alternatives aims to distribute 500 of their patented start-up kits, each including a manual for setting up a hydroponics growing system and links to useful Web sites and other resources. This summer, they'll be conducting workshops in the TelUQ rooftop garden and hope to take the sessions into community centres around the city in coming years. With a grant from the International Development Research Centre (IDRC), Alternatives hopes to establish a research centre abroad this winter, either in Cuba, Senegal or Morocco.

Cooler, greener summers

In a related effort, the Urban Ecology Centre's (UEC) Green Roofs Initiative is promoting the use of extensive green roofs as a means to improve the city's environmental friendliness. Last year, Montrealers suffered 64 days of poor air quality. An inadequate water treatment record once forced us to consider privatizing the service. And the urban heat island effect - on hot summer days, temperatures in the city are two to three degrees Celsius higher than surrounding areas - has become an increasingly pressing issue.

Green roofs not only naturally filter airborne pollutants but Environment Canada estimates that converting just six per cent of roof space in Toronto to green could reduce summer temperatures by one to two degrees and save up to five per cent in energy costs. The results for an area like the Plateau, one of the most densely populated in the country, could be even better.

Furthermore, on heavy rain days, green roofs can retain more than 50 per cent of what would normally be dumped into the city's storm sewer system. Finally, while the soil insulates a home during winter, it also protects it from sun rays in summer, which can reduce or even completely eliminate the need for air conditioning.

"In 10 years, this kind of thing will be taken for granted," says Owen Rose, a member of the board at UEC who has been developing the Green Roofs Initiative and an architectural intern at Smith Vigeant Architectes, a firm known for its green projects.

Next year, the UEC will establish a sample green roof atop a triplex to encourage surrounding homeowners to follow suit. Eventually, they too hope to conduct workshops throughout the community. For now, they want to show people what green roofs can do and assuage fears that they're too expensive and complicated to implement. In fact, converting a conventional roof to green does cost two to three times more than simply replacing it. However, advocates say a green roof will last twice as long as a regular one. Over time, an estimated 10 to 20 per cent per year can be saved in energy costs.

Neighbourhood fun

The UEC is focusing its efforts on advocating the conversion of existing roofs, which is more expensive than incorporating green roofs into new buildings from the start. Structural modifications are minimal for extensive roofs and usually interior renovations can be avoided altogether. The UEC hopes its research will ultimately convince the city to establish subsidy programs for rooftop conversions from conventional gravel to green. The research will also make a case for implementing green roof requirements in new buildings.

"It's also for the beauty of it," says Hill. Planting roof gardens atop schools and other public buildings can strengthen a community by creating unique places for people to gather and participate in a rewarding, wholesome activity. In these uncertain times of climate change, it's nice to know that exercising your green thumb can actually make a difference.