In anticipation of the long weekend, many New Yorkers have been desperately planning their escapes from the concrete jungle. For a fortunate few, such as Philip Roche, the great outdoors lies just outside their apartments.

Mr. Roche and his friends will enjoy the July 4 fireworks from his sprawling, 2,500-square-foot rooftop garden in Long Island City with unobstructed views of the East River, 57th Street, the Chrysler Building, the Empire State Building, and the Queensboro Bridge.

While Mr. Roche has a country house on seven acres of land in New Jersey, he’ll opt to stay in the city for July 4. “With a garden like this, you’re just not as desperate to get out of the city,” he said.

Mr. Roche, 43, co-owns and runs Plant Specialists, a firm that designs, installs, and maintains rooftop and backyard gardens in the city. He immigrated to America from New Zealand about 15 years ago; he planned to come for a vacation, and never left. One look at his home and it’s apparent why.

Mr. Roche lives in a sleek, minimalist, industrial-style loft on the top floor of a former factory complex off the East River. His 1,000-square-foot apartment was once a machine room; it has a raw concrete ceiling that hasn’t been touched since 1900. He has made changes to the apartment to make it homier, including painting over dusty and hard-to-maintain brick walls, and building a concrete-and-stucco boxlike structure in the middle of the space that houses the bathroom and closets on one side and a kitchen on the other.

Two of Mr. Roche’s friends, Tim and Dagny DuVal, own the building, which was once an iron factory, then a paint factory, and later an ice cream factory. The DuVals, former owners of Plant Specialists, now split their time between their Long Island City home and Italy.

The building houses Plant Specialists, along with about a dozen or so other businesses.

When the DuVals bought the building around 1982, they were true Long Island City pioneers. “It was all burnt-out cars and prostitutes,” Mr. Roche said of the neighborhood, recalling a particularly scary walk he took from Manhattan to visit the DuVals.

While the neighborhood is still industrial, Mr. Roche’s home is a hidden gem. The real treasure is not the apartment he shares with his partner, Doug, and their dog, Snoop, but the garden they share with their friends and landlords.

“Mrs. DuVal is the passionate gardener,” Mr. Roche said, “We just get to use it and enjoy it.”

Mrs. Duval’s passion for gardening shows itself in a large, funky outdoor oasis that feels miles away from the hustle and bustle downstairs. The garden space, which was once used to store stainless steel vats for the Mayflower Ice Cream company, features a copious mix of trees, plants, and flowers, with an abundance of green leaves and foliage. There is a weeping Japanese red maple tree that looks like a giant bonsai, Japanese black pine trees, red twig dogwood branches whose sticks turn red in winter, cacti, hydrangea, butterfly bush, lots of hosta, tropical mandevilla, lavender, and herbs such as chive, sage, and basil.

There are big communal spaces as well as small nooks, and on the ground lie old Chinese stone slabs and textured concrete paving slabs interspersed with stones.

The building’s exterior is covered with Boston ivy, which turns the whole structure green in spring, and red during colder months. Mrs. DuVal has filled the garden with about 50% hearty evergreens and perennials, something Mr. Roche advises clients to do so their gardens will survive and even flourish through the city’s extreme weather. “Rooftops are harsh environments. What grows in a suburban backyard may not work on a New York City rooftop garden,” he said.

In the spring, Mr. Roche and his business partner, Grahame Hubbard, order a shipment of tropical flowers from Florida for their clients, and some for the garden as well. In fact, Mr. Roche said he takes inspiration from his personal garden when working with clients, incorporating many of the same kinds of plants and planters. “This garden is a lot like the ones we design,” he said. “But on a much larger scale.”

The DuVals and Mr. Roche often entertain on their roof deck, with casual barbecues, parties, and sit-down dinners. A 12-seat table stands under a pergola covered in wisteria; it is made from timber from the old ice-cream factory refrigerator. The industrial theme continues with a fountain made out of a rusty iron wheel from the factory.

There is also plenty of outdoor furniture. “I usually have my coffee right here,” Mr. Roche said, pointing to a small area with a set of stone-and-concrete table and stools, and a backdrop of city skyscrapers.

Some of that view may soon become slightly obstructed. Directly across from Mr. Roche’s building, Silvercup Studios plans to build a Richard Rogers-designed complex that would include apartments, retail space, and a waterfront esplanade. He says he welcomes the development, which will replace a much-protested power plant that now sits on the waterfront and intermittently makes a lot of noise.

With an outdoor oasis like his, it’s hard to imagine that anything going on downstairs could dampen his spirits.