a spiraling ETFE roof tops 'the leaf' botanical gardens in canada

kpmb architects shapes a greenhouse garden in winnipeg

A new botanical garden, The Leaf, has taken root in Winnipeg‘s Assiniboine Park, inviting visitors to immerse themselves in the world of plants and nature. Designed by KPMB Architects in collaboration with Architecture49, Blackwell Structural Engineers, and HTFC Planning & Design, The Leaf brings 35 acres of sustainable architecture and lush gardens to Manitoba. With its spiraling glass rooftop, the greenhouse-style project marks KPMB Architects’ first venture into the realm of horticultural design, aiming to foster a deeper understanding of the natural world while setting an impressive precedent for future endeavors.

images © Ema Peter | @emaphotographi

Assiniboine Park’s new icon

The Leaf is an important addition to the Assiniboine Park Conservancy’s ambitious redevelopment plan, which has been breathing new life into this century-old park since 2009. The architects at KPMB have designed it as an extension of the park’s existing attractions, including the Assiniboine Park Zoo, to create a dynamic and engaging ecosystem that is both educational and architecturally-minded.

At first glance, The Leaf celebrates the dialogue between architecture and nature, with its distinctive roof design informed by the Fibonacci sequence, a mathematical phenomenon often found in the spirals of sunflowers and nautilus shells. The complex cablenet structure gracefully unfurls around the building, reminiscent of a blossoming flower. Ingeniously placed lights and reflectors within the building replicate the atmospheric effects of natural moonlight, thunderstorms, and the Northern Lights. This organic, curvilinear form beautifully mirrors the simplicity and complexity of the diverse plant species it houses.

glass walls enveloping the structure open toward panoramic views

A Hub for Botanical Education and Exploration

Comprising four distinct biomes, The Leaf hosts over 12,000 trees, shrubs, and flowers, and 400 unique plant species. Visitors embark on their journey in the Hartley and Heather Richardson Tropical Biome, which features a meandering pathway and Canada’s tallest indoor waterfall. The Mediterranean Biome showcases a vibrant tapestry of colors, textures, and fragrances from Greece, Italy, South Africa, and Chile. The Babs Asper Display House dazzles with rotating floral displays, exploring seasonal and global themes, while the Shirley Richardson Butterfly Garden offers a canopy walkway overlooking the Tropical Biome. Glass walls enveloping the structure open toward panoramic views, blurring the line between interior and exterior, and allowing visitors to take in the surrounding landscape.

the complex roof structure unfurls around the building to recall a blossoming flower

The Leaf ranks among Canada’s largest Ethylene Tetrafluoroethylene (ETFE) buildings, demonstrating the material’s superior thermal performance compared to conventional greenhouse materials. Winnipeg’s extreme temperature variations demand robust solutions, and the ETFE roof delivers with exceptional transparency, ensuring enough sunlight reaches the indoor biomes. Natural ventilation and an open-loop geothermal system, powered by subsurface water flow, maintain optimal temperatures within the biomes, while mist fans provide cooling for both plants and visitors, ensuring a comfortable environment.

the garden features a meandering pathway and Canada’s tallest indoor waterfall

‘As Winnipegger’s we celebrate the extremes of our climate, however even the hardiest of us appreciate a break from the long cold dry winter,’ writes Lee McCormick, Managing Principal at Architecture49 Manitoba. ‘The Leaf is an affordable, approachable and accessible urban oasis in the winter desert that transports one temporarily away and connects all people to plants in faraway lands. The facility is a fantastical technical achievement that elevates the spirit through the amplification of the natural systems to allow visitors to reawaken their appreciation of the horticultural world while the outside world is in hibernation.’

the project creates a dynamic new ecosystem that is both educational and architecturally-minded