The people of Cornish Road weren't impressed by the apple tree. It was the 1980s in Toronto's leafy Moore Park neighbourhood, and the Houghs – the landscape architect Michael Hough and his wife, Bridget – had planted one in their front yard. Even more uncouth were the tomatoes, green beans and lettuce. To Mr. Hough, this was just good sense: Why pour water and energy into a lawn, when you could put the soil to better use?

"Michael lived by his principles," says his old friend, Simon Miles. "This upset many of the neighbours, but Michael felt it was the right use of the south sunlight."

Mr. Hough, who died in January at 84, spent his career in pursuit of this ideal – the integration of cities with natural systems. As a young landscape architect in the 1960s, he helped lead that profession to combine urbanism and ecology, to think of human activity and nature as complementary and connected.

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His own design work included Ontario Place and the University of Toronto's new Scarborough campus, as well as advocacy that helped clean up the polluted Don River and preserve the historic Don Valley Brick Works.

But it was his teaching at University of Toronto and York University, and his books – including Out of Place (1990) and Cities and Natural Process (1995) – that helped cement his thinking. The ideas were deep and prescient. Today, cities across North America are working to repair their ecologies and make room for urban agriculture. "Landscape urbanism" is a powerful movement, and Mr. Hough's legacy is very much alive.

He was always at home in nature and in the city. Urbanity was bred into him: the son of a British diplomat, William, and a Frenchwoman, Hortense, he grew up as his father's career took them to Istanbul in the early 1930s, then Madrid and Prague, with winters skiing in Switzerland with his mother's family.

It was a cosmopolitan life. His parents were both amateur musicians, and when composer Béla Bartók came to Istanbul, he stayed with them – leaving a signed copy of one of his pieces for young Michael.

Yet despite the glamour, he was "largely raised by servants," says his widow, Bridget. When the Second World War broke out, he had just arrived at boarding school in England. He was 10. His parents were posted to Palestine in 1939, and he would not see them again until he was 16.

This experience, Ms. Hough says, fed a solitary and unconventional streak in his personality – and also a love of the natural world. "The family really felt he took refuge in nature and art when he was lonely," she says. "And I think he was quite a lonely child."

However, he came out of that solitude as a compelling, charismatic and driven character. After two years as an officer in the British Army in Malaysia and Singapore, he returned to Britain to study at the University of Edinburgh. Here he showed prodigious skill with a paintbrush, talent as a designer and much charisma.

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Back in Edinburgh, he was drafted into a production of Romeo and Juliet as Lord Montague. Playing Lady Montague was Bridget, then 17, and the two soon fell in love. "He seemed very exotic," she recalls, with his French heritage and his experience of the world.

Back in Britain, Michael found himself unfulfilled as he worked in the London office of prominent architect Basil Spence. The answer came from an iconoclastic architect named Ian McHarg, who had strong ideas about "ecological planning." Mr. McHarg, who had taught Mr. Hough at Edinburgh, was starting a landscape architecture master's program at Philadelphia's University of Pennsylvania. "For all the people hoping to go to America, this was an opportunity," Ms. Hough recalls.

Mr. McHarg was a seminal figure. His book Design With Nature helped nudge city planning and landscape architecture toward paying attention to ecological facts: climate, soil conditions, plant life. Mr. Hough later had differences with Mr. McHarg, but those studies helped shape Mr. Hough's approach.

First, though, he and Bridget toured America in their "tomato-soup-coloured 1957 Volkswagen Beetle," she recalls. They wound up in San Francisco, where their son Tim was born.

Soon they were forced, as Mr. Hough's visa expired, to return to Britain. "Nobody in England seemed to know what landscape architecture was," his wife recalls. So they set out for another land of opportunity: Canada.

They landed in Toronto in 1959, and found a city and a country bursting with potential. By 1962, Mr. Hough was working on the Toronto suburb of Don Mills, a groundbreaking example of modernist city planning, with a new generation of modernist architects.

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In 1965, he founded the University of Toronto's Landscape Architecture program, and held a job in the university's campus planning office. His boss asked him to draw up plans for new suburban campuses; Mr. Hough talked himself into a comprehensive job on the new Scarborough College. That building's architecture – by Australian émigré John Andrews, who also designed the CN Tower – was praised by critics around the world.

At Scarborough, set in the wooded Rouge Valley, "Michael immediately realized you couldn't build on the valley land," Ms. Hough says. "They came up with the idea of this toothpaste-tube-like building along the valley wall." The results were beautiful and innovative and kept buildings away from the low-lying, flood-prone areas.

Mr. Hough began teaching at York University's new Faculty of Environmental Studies in the 1960s, a role and an environment that he loved. He continued to teach, and speak publicly on ecological issues, even as his design firm grew in size, working on individual landscapes as well as urban and ecological planning.

"He never stopped working," Ms. Hough says. "He was driven, obsessed, but I suppose all of these are good when you want to change the world."

His passions came down to his family, too. "He taught me all about ecology, natural history, evolution and Darwinism," says Tim Hough. "From an early age I was hooked."

He was a classic "absent-minded professor," Tim adds, and his family, "TimTum," Adrian (Fluffkin) and Bridget (Tweetles") shared his deep connection with nature.

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Their cottage, in the bush north of Huntsville, Ont., was "Michael's laboratory for experiments in ecological living," says Ms. Hough, who became a medical illustrator.

Mr. Hough's environmentalism was not always popular, as his longtime colleague Carolyn Woodland recalled at his memorial. "Being truly green in those days was a constant struggle," she said. "His unflinching perseverance, and sometimes lack of diplomacy, earned the office the nickname Huff and Puff; sometimes it was used affectionately – and sometimes not."

Hard-headed, articulate and charming, he retained the ability to inspire his staff, students and clients, Simon Miles says. "I've never met someone with such bright, twinkling eyes, and because he was always talking such sense, and with such passion, it was a pleasure to listen."

Mr. Miles, a policy and international development consultant who knew Mr. Hough for nearly 50 years, says there was a solid through-line in all Mr. Hough's work. "He was a big-picture thinker. He loved his fundamental principles of landscape design."

And he was always concerned with putting them to practical effect. For instance, Mr. Miles cites one idea from Mr. Hough's book Out of Place: to work with economies of scale. He did so with his landscape design at Ontario Place, on which he collaborated with the architect Eberhard Zeidler and won an award from the Canadian Society of Architects in 1975.

"They needed a means to create more land and to break the waves," Mr. Miles recalls, "so they got some old tankers, filled them in and sunk them."

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Others of Mr. Hough's projects were quietly influential – like the courtyard at the University of Toronto's Earth Sciences Building, a remarkable square of boreal forest he seeded with native species and allowed to blossom into a tiny, perfect expression of nature's will.

Mr. Hough was an influential figure at the University of Toronto, briefly, and then for decades at York. Mr. Miles attributes this to his ability to communicate: "He made his ideas simple to take on board."

In later years, Mr. Hough continued to be influential within his profession, but also made an important impact on his city: His firm designed a master plan in the 1990s for the site now known as the Don Valley Brick Works, and he was a force behind the citizens' group Task Force to Bring Back the Don. He contributed to the Royal Commission on the Future of Toronto's Waterfront, which wound up in 1992, and had deep and lasting effects: The reclamation of the Don Valley, and the nearby Toronto Port Lands, are now a crucial part of the city's multibillion-dollar waterfront regeneration plan.

And despite many awards, it was the growth of his ideas and his work that pleased him most. "He loved teaching and influencing young people, but he was never satisfied with the status quo," Ms. Hough says. "It was always about looking forward."