Michael Doan Hardy, 84, a community advocate whose environmental activism helped change the landscape of West Philadelphia, died Monday, July 19, at Rittenhouse Hospice of respiratory failure.

Mr. Hardy spent more than 50 years in West Philadelphia, planting trees, creating urban green spaces, and helping to make it a more vibrant, welcoming community. He was a founder of the Friends of Clark Park, chaired the University City Historical Society, and led or supported many other organizations devoted to community planting and gardens.

The Arbor Day Foundation, a national group, honored him in 2009 with its Lawrence Enersen Award for his grassroots work.

“Mike was a kind, caring and wonderful soul,” said University City District president Matt Bergheiser in a published tribute. “Behind his gentle and calm presence around University City lay a burning desire to make the neighborhood better and a deep love for his community and his neighbors.”

Raised in Navasota, Texas, Mr. Hardy was one of two children born to Crittendan and Eula Hardy. He received a bachelor’s from Rice University before entering the Navy. He was stationed in Japan and became fluent in Japanese. After the service, he earned a master’s in American studies at the University of Pennsylvania.

From there, Mr. Hardy began a 30-year career teaching history at the Community College of Philadelphia when it opened its doors in 1965. So did Barry Grossbach, the man who would become his partner and eventually his husband of more than 50 years. Mr. Hardy — focused, passionate, always firm in his convictions, knew early on they were meant to be together. Mr. Grossbach required some convincing.

“I just couldn’t stand him,” Grossbach said. “Michael was a very determined individual. It was a personality conflict. But he decided I was the one. And he was very persistent.”

One of the seminal years in their relationship was 1968. One day, the two historians sat together on Independence Mall, addressing envelopes for Democratic presidential candidate Eugene McCarthy in his primary campaign against President Lyndon B. Johnson.

“I guess we started talking. It just changed things,” Grossbach said.

The other year of significance was 1970. That’s when they bought the house where they would reside together for more than 50 years in West Philadelphia.

“We had no role models,” Grossbach said.

In fact, he said, when they were at first turned down for a mortgage, it wasn’t because they were a gay couple. Rather, the loan officer assumed they were two heterosexual men and that one would eventually get married and leave the other unable to afford the mortgage payments alone, he said.

But they did get the financing to buy a house, and they built a life. They were community activists together, each working on his own projects but supporting the other’s. Mr. Hardy’s always involved gardening and landscapes; he was so committed, he would weed strangers’ gardens as he walked by. The couple traveled together, enjoying Prague, Barcelona, northern Italian hill towns, and other destinations. Mr. Hardy made sure his community projects were cared for while they were away.

Theirs was a deep partnership.

“Our lives were totally intertwined,” Grossbach said.

Last year, the couple erected a stone in Woodland Cemetery in University City on a plot they purchased years before. Even though they intended for their ashes to be scattered together in various locations of significance after both died, they wanted the stone to be a permanent marker in the neighborhood where they made their home.

The inscription on the stone reads:

Together 50 years and counting

“They did it their way”

On the site of their plot, Mr. Hardy planted a tree.

“For him,” said his husband, “trees were an environmental necessity and also a thing of beauty.”

In addition to Grossbach, Mr. Hardy is survived by his sister, Margaret Dyer, and other relatives.

There will not be a memorial service or formal burial. A community celebration of his life’s work will be held Tuesday, Sept. 21, at Bartram’s Garden. The exact time will be announced later.

People who wish to honor Mr. Hardy are encouraged to donate to a local environmental group of their choice, or, as Mr. Hardy would say, “Go plant a tree.”