Civic pride

The curving towers, podlike council chamber and sweeping lines of Toronto’s City Hall long ago earned the modernist complex, by Finnish architect Viljo Revell, a cherished place in the city’s imagination of itself. Despite the popularity of the overall scheme, however, Revell’s daring artwork always had one weak spot: the flat roof of the podium from which the towers rise. This 36,000-square-foot vastness of grey concrete pavers was dull and uninviting, and it lacked the drama that distinguishes the project as a whole.

It is certainly dull no longer. With the recent opening of the garden that covers most of the podium roof, a new, vivid park has emerged in the heart of the city. Vibrant colours — yellow and orange, red and purple — splash the green expanse throughout the growing season, while pathways and seating areas crafted by Toronto designer Adrian Blackwell invite visitors to stroll and linger amid the plantings.

The new green roof is the $2.3-million first phase of a larger revitalization of City Hall and the adjacent Nathan Phillips Square that is expected to total $42.7 million. Designed by the Toronto-based firms of Plant Architect and Shore Tilbe Irwin & Partners, the garden has been built tough to endure the harsh heat of summer and the cold of winter, and to enhance permanently the square and building going forward.

“The starting point for this entire project came from thinking about the meaning of civic space and where civic spaces came from,” Christopher Pommer, principal at Plant Architect, says. “It reinforces the idea that Revell put there in the first place, about having a major public open space with a very direct formal relationship with an exposed council chamber. This is the first time a council chamber was not buried in the building, but rather held up in front of the public square. A major part of the strategic plan for the square is to reactivate those spaces, to make more and better connections to the elevated walkways, visually and physically, to open up that incredible space underneath the two towers and the council chamber. I think that’s where the impulse to turn up the volume on that podium roof came from.”

The basic plant of the scheme is sedum, a low, hardy succulent that comes in a large variety of colours and textures and is well suited for installation on dry, windy rooftops. Over the last winter, this material was sprouted in small, shallow plastic trays of growing medium, and then, come spring, it was moved, containers and all, to the roof. The result is a fine rectangular grid of sedum, tall grasses and many perennial flowering species chosen for their colours, varying heights and different temperaments regarding sunshine and shadow. Pre-growing has meant that the garden is well rooted and ready for visitors in its very first summer. An irrigation system will nurse the plants along during the garden’s first two years, Pommer says. After that, rainwater should be enough to keep it going.

The designers have been mindful of Revell’s strong east-west orientation of the City Hall buildings and site, and have laid out the garden to align with this directionality. It has also been crafted with urban amnesia in view: the roof has been closed to the public for the past 15 years, and many citizens have forgotten that there is anything to visit above the level of Nathan Phillips Square. Hence the big, conspicuous circular planter, with its three Kentucky coffee trees, standing at the top of the ramp leading up from the plaza to the roof. “The trees are meant to be a beacon,” says Pommer, “declaring to people on the ground that there is something up there.”

What they find up top will change as the garden matures and settles in over the next several years. The seeds of flowering plants will drift from one tray to another, softening the garden’s geometry and blending its colours. The tight sedum mat will likely flourish, and, with routine weeding, it should provide a robust platform for the many floral and grass species.

With the launch of this green civic initiative, a once-forlorn part of the metropolis has been reclaimed, and Toronto’s public realm has been enriched. CI