It's called mosaïculture, it sometimes features plant-based works that spread across entire city parks, and it's a centerpiece of this year's Canada 150 celebrations in Gatineau, not far from the Canadian capital of Ottawa in Quebec.

Yet the first thing to understand about mosaïculture is that it really isn't topiary. The idea of shaping plants into artistic objects is the same driving impulse, but not the same technique. Topiary usually involves precision pruning of one shrub or tree, rather than a collection of thousands of plants growing on aluminium or steel frames and blossoming to reveal stunning and complex works of art. Like mosaics, the elements are lovely in themselves but it's the big-picture view that reveals the intricacy of the art.

Comier is the founder of Mosaïcultures Internationales de Montréal, established in 1998 and a world leader in mosaïculture techniques and training. International competitions began in 2000, with 35 participants from 14 different countries. They've been held every few years since, with hosts in Shanghai, China, and Hamamatsu, Japan, before returning to Canada for the next few competitions.

The artistic expression appears a blend of sculpture and painting, built upon the aluminium scaffolding. As in a museum, visitors tour various works reflecting different artists and styles. They are as whimsical as a row of ring-tailed lemurs celebrating Madagascar, or as enigmatic as China's "A True Story" and a woman created entirely of cascading flows of flora.

In 2013, for example, mosaïculture designers in Comier's signature event used some 22,000 species in dozens of displays. For scale, consider that "Bird Tree" was the tallest at more than 15 meters high, and it took at least 30 people to assemble the piece.

It's rare to think of gardeners using cranes and front-end loaders and other heavy equipment, but it's necessary to complete some of the mosaïculture works. Behind-the-scenes videos demonstrate how welders, cherry-picker utility truck operators and others build frame segments and then place them in sequence – almost as if they were building a three-dimensional puzzle – as the sculpture is constructed.

Once the structural components are placed, the plants and shrubs are filled in according to design. In the case of "Mother Earth," a mosaïculture work that Comier designed, that means completing a mosaic for a sculpture that runs 7.6 meters high and includes a waterfall; in the case of "The Man Who Planted Trees," inspired by the Jean Giono novel, the sculpture is actually a tableau of 10 art pieces needed to create the complete scene. The latter installation required nearly 35,000 plants to complete in 2013.

For the Canada 150 celebration, between 40 and 50 mosaïculture works will be displayed along a 1-kilometer trail in Jacques Cartier Park in Gatineau. The MosaïCanada 150 exhibition, organized by Comier's group around the theme of Canadian culture and history, is expected to take about 90 minutes to complete, and is free to the public although guided tours will be available for a nominal fee. Canadian officials estimate that nearly 1 million people will see it during its run between July 1 and October 15.

For more information about the exhibit, see MosaïCanada 150's link.