A habitat for wildlife
In Etobicoke, Ontario, gardener Christina Sharma also saw the benefits of turning a barren rooftop into green habitat. The founder of Project Chirp, a songbird conservation initiative that promotes the planting of native species in home landscapes, Sharma and her husband were having a 3.6-by-3.6-metre family room addition built on their home, and decided to crown it with a green roof: “I wanted a garden that would provide songbird and pollinator habitat.”
Sharma contracted Nedlaw Living Roofs & Walls of Breslau, Ontario, to install the roof, which was completed this past November. In keeping with Sharma’s wildlife habitat goal, the plantings are composed of native meadow vegetation, comprising 80 per cent prairie grasses, including sand dropseed, sideoats gramma, Canada wild rye and little bluestem, and 20 per cent wildflowers, such as lance-leafed coreopsis, black-eyed Susan, wild bee balm and hairy beardtongue (Penstemon hirsutus). “My ultimate goal,” says Sharma, “is to bring nature to the city, so I don’t have to go up to Muskoka to experience and enjoy the songbirds.” [Note: The city of Toronto’s Green Roof Incentive Program provides grants to homeowners installing them.]
While many European green roof plantings and larger institutional installations in North America stick to tried-and-true sedums because they’re proven performers in harsh rooftop conditions, a few Canadian practitioners are pushing the plant palette envelope and, as with Sharma’s roof, are using native species.
Jeremy Lundholm, an associate professor in environmental studies and biology at Saint Mary’s University in Halifax, is conducting controlled green roof experiments, growing plants indigenous to the coastal barrens ecosystem of Eastern Canada. “Rooftops are urban environments that mimic the dry, rocky conditions found in a number of natural habitats,” says Lundholm. On a rooftop at SMU, he has trial plots where natives such as harebell (Campanula rotundifolia), Potentilla tridentata and silverbell (Solidago bicolor) thrive in just six centimetres of growing medium. “We’ve had a high survivorship rate—85 to 100 per cent,” says Lundholm, noting that even in Halifax’s notoriously harsh and unpredictable winters, these plants are performing well. “We often think of green roofs for their summer benefits in terms of reducing the need for air conditioning, but in this climate, I’m more excited about the winter benefits—the effect of plants trapping snow and providing insulative value.”