Designlines Magazine: The Allan Gardens Palm House Prepares to Host the Ultimate Garden Parties

By Eric Mutrie

Photography by Adrien Williams

Fresh from a three-year restoration, the architectural landmark is back to showcase horticulture and design history.

Until this spring, visiting the domed Palm House pavilion that anchors Toronto’s Allan Gardens Conservatory greenhouse complex felt like walking into a fever dream—meaning that you’d find a magnificent jungle of palm trees waiting inside, but you’d probably work up a serious sweat, too. “Four years ago, it would have been unbearable,” says Matthew Firestone, an associate architect at Zeidler Architecture. “When we first came in, we were drenched,” echoes David Eckler, a principal at the architecture firm AREA. Even more concerning, there had been reports of leaks and falling glass panes. All this to say, the Palm House of the past was not exactly an ideal wedding venue. Yet in 2022, the Friends of Allan Gardens and the City set out to make it one—enlisting Zeider as lead architect and AREA as heritage architect for an extensive, $11-million renewal of the 1910 building that would overhaul its HVAC systems and restore its structural integrity.

In May, with both goals achieved, the Friends of Allan Gardens reintroduced the landmark (originally designed by then-City of Toronto architect Robert McCallum) as a dignified event space available to rent for all manner of social functions. By day, the revamped Palm House remains open to the public for free, and is stepping up its community engagement efforts, too. Programming has already included a puppet show and a performance by circus entertainers dressed as bees and flowers. The only tradeoff? The towering foliage inside has undergone some pruning. Tropical greenery still lines the perimeter in curved planting beds, but the centre of the room is now a concrete floor featuring miniature trees-on-wheels that can be rolled in and out for greater flexibility. (Other plants were relocated to Cloud Gardens and Centennial Park Conservatory during construction.)

Fortunately, there are plans to gradually reinstate the dense jungle of the past. In the short term, Michael McClelland, founder and chair of the Friends of Allan Gardens, says the volunteer organization will be increasing the number of palms “gradually over the coming months.” Moreover, the long-term ambition of the group is to develop other onsite event spaces that will, eventually, absorb hosting duties and allow for more of the Palm House to once again be dedicated to big, permanent gardens. “The existing Palm House conditions are temporary until we expand the conservatory,” he explains. “Once the conservatory has been expanded, we will look at more intensive plantings in the Palm House. Our intent is to double the space for diverse and exotic flora, enhancing educational and recreational opportunities for Torontonians.” This full plan is outlined in Growing With the City: An Ecosystem of Initiatives for Allan Gardens [PDF], a 2023 publication by Friends of Allan Gardens.

That one, hopefully, temporary drawback aside, the other changes made to the Palm House during its revitalization all represent exciting returns to the building’s roots. The major updates start at the entrance. At some point in the 1920s, the eastern portico that had initially served as the building’s main access point was removed and replaced with a flat wall of windows, bookended by two smaller doorways on either side. Now, the Palm House’s central entry point has made its triumphant return, rebuilt with sandstone sourced from the same Indiana quarry that provided the building’s original materials. Look up above this new doorway, and you’ll spot another fun detail carried over from the original Palm House design: Union Jack-like windows, which match a row of similar clerestory windows above. “It was a very British-oriented project,” says Eckler. “They were looking to the Kew Gardens in London.”

Apart from establishing a proper event reception area, the reinstated formal entrance is also important for being wide enough to fit a scissor lift through, facilitating easier servicing of the glazed rotunda. This in turn allows for a newly streamlined interior service catwalk, reducing visual clutter and improving sightlines of the completely rebuilt dome up top. (Aluminum mullions, themselves a 1970s replacement for the original wood versions that had to be replaced every few years, were preserved.) As the firm that led the recent revitalization of the Eaton Centre’s galleria skylight roof, Zeidler knows its way around a glass ceiling, and its work here marks another clear triumph. Some 1,200 new panes of modern glass adopt a ceramic enamel treatment that delivers another big improvement to visibility. “Typically, what they’d done each summer before was whitewash the glass — paint it white to help with solar heat and then just let it fade. It didn’t look particularly nice,” says Firestone. “We were able to introduce this frit that you can’t even really see from here, and that helps from a maintenance perspective by being a permanent solution. And now it’s a much more temperate environment.” The fritted pattern is applied in a gradient, so the southern areas that receive the most exposure are tinted the darkest.

Of course, this frit system is just one aspect of the revamped building’s larger climate control strategy. As in the building’s previous iteration, cool air is still carried in from tunnels running underneath the concrete floor, then flows out through the clerestory windows above. “Originally they would have had to be cranked open when it gets too hot, but now they open automatically on actuators,” says Eckler. The most significant upgrade is a new rooftop AC unit stationed atop the adjacent boiler house. “It’s interesting working in old buildings—there is so much behind-the-scenes work that wouldn’t necessarily be apparent, but is all part of the process. To support that new unit on the roof, we had to reinforce the whole structure inside,” says Firestone.

Other subtle yet important structural upgrades include rehabilitated steelwork in the Palm House itself. At the start of the design process, Zeidler and AREA utilized a LIDAR scanner to develop a 3D model of the pre-renovation structure. One of the biggest revelations? The building is actually on a subtle slant. “We’d see points in the model that weren’t lining up and we realized that over 100 years, the building had settled unevenly,” says Firestone. As a result, while the building may appear symmetrical, it now requires differently sized panes of glass on each side. The complexity of the project also meant that, during construction, the entire structure was encased by an outer shell of scaffolding. “It became a building within a building, which allowed the team to work throughout all four seasons, replacing the glass and doing all this work in a controlled environment,” Firestone continues.

Walking into the newly restored pavilion, it might be easiest to spot what’s missing—namely, a greater abundance of palm trees. In part, that’s a testament to how faithfully the building’s other components were restored. Thankfully, much like the structure’s eastern portico, its towering palms seem set to make their grand return down the road. That’s a big relief. While the revitalized landmark in its current form may already represent a significant achievement in architectural conservation, it will honour its past even more as it blooms into something leafier in the years to come. No matter how many memorable events it plays host to in the meantime, the Palm House’s indoor forest has always been the real cause for celebration.