When one thinks of the outdoor living spaces in highly urbanized areas like New York City, what usually comes to mind is small spaces and lots of impervious surfaces. When Annette Bonus looks at those spaces, she sees opportunities and promise.

One of the benefits of urban container gardening is the ability to switch out plants and flowers and recreate a new look just by rearranging the containers.

Bonus, the owner of Rooftops Gardening, also known as Bonus Gardens, takes the most barren-looking terraces, rooftops and brownstone backyards and transforms them into spaces that are aesthetically pleasing oases.

Bonus came into landscape contracting later in life. She was in her early 50s and a veteran of the commercial printing industry when the industry started losing its viability in the contemporary marketplace. “I knew I had to find something else to do,” she says. A friend asked her to design a rooftop garden. “It was one of the best experiences of my life,” she says. For a year, Bonus held on to her job at the printing company and did landscaping work on the side until she decided she would be able to make a living at it. “I quit the other job and I haven’t looked back since,” she says.

Through assertive networking, Bonus developed a client base that started with developers and branched out to include homeowners, renters, interior designers, building owners and managing agents. One of her earliest jobs was to design and install 20 terrace gardens at a boutique hotel on Manhattan’s Upper West Side.

Here, plants are layered along a narrow pathway, with the largest in back and the smaller in front.

Each year, she doubled her customer base, serving Manhattan, Brooklyn and sometimes Long Island. “It was an amazing transformation,” she notes. “One of the reasons is there weren’t a lot of people like me who knew how to do container gardens, roof gardens, terraces and penthouses – and now it’s a wonderful business. It’s getting much, much more competitive.” For Bonus, the increasing competition means keeping up marketing efforts. Utilizing the skills she developed in the printing industry, she has attained success through direct-mail efforts, and she also uses LinkedIn, Twitter, Facebook and has a website. “If I can get in the door, I can usually sell the job,” she says.

Hiding pipes is easy with trellis pieces, planters and pots.

It’s not just New York City residents who live in small spaces and crave beauty in their small outdoor spaces. An aging Baby Boomer population means many people are trading in their single-family residences for townhomes, duplexes or condos, but still want an attractive outdoor space.

When Bonus looks at a space, she considers its size, shape, degrees of light and shade, functional opportunities and the customer’s budget for filling that space. She creates a plan that includes hardscapes – such as paving, structures, pots and planters – and landscape materials, such as trees, shrubs and perennials. She can design a “contained and secluded” space or use the city skyline as an open panorama.

The biggest challenge in New York City landscaping is transporting equipment and materials up several stories. “When you’re doing container gardens, you have to get all of those bags up there, and they weigh about 50 pounds each,” she says. “Sometimes you have to go up a flight of stairs with those bags. That’s a big, big challenge. The other aspect of this type of work is that you have to get an OK from the building engineer, architect or manager about the weight of the planters, because you can’t just put planters up there,” Bonus says. “You’ve got to go within the approved pounds per square foot, and then you can use soil manipulations to get it in line with the limit. There are a lot of technical aspects to it.”

In creating a garden for a brownstone backyard, light is a significant consideration. “Sometimes you’ll have a building or trees blocking the light,” Bonus says. “The soils in these backyards are generally very, very poor. They’re compacted in clay, so you have to redo all of the soil.”

Because most brownstone garden spaces are long and narrow, Bonus seeks to create interest in terms of a view. “You want to vary the path and the view,” she says.

In creating a garden for a terrace, Bonus will take into account an area for lounge chairs and tables for outdoor eating. “There are views that you don’t necessarily want to block, but you want to be able to have an environment that feels as if you’re not in the city,” she says. “You want to enclose it in a certain respect. If you have a large enough terrace, you want to create a couple of ‘rooms.’ The other aspect of terrace gardening is you want to have irrigation up there.”

Bonus works with a dedicated irrigation company to provide the on-site water system. “You have to vary the amounts of water in the system,” Bonus says. “The higher up you go, the more arid, the more desert-like it is. I work with them to get the right amount of drip.”

One of the most important factors in gardens today is low maintenance, Bonus says. “That means maintenance in terms of water,” she says, adding that she chooses landscaping materials that don’t require a lot of water. “Knowing what goes there is important,” Bonus says. “If you don’t know your species, you’ll make a lot of mistakes, lose a lot of plants and get very discouraged.”

Water remains a concern even after an irrigation system is installed. “We had a summer last year in New York where we had almost three weeks of 100-degree weather,” notes Bonus. “It was horrible. We were really busy. One of the problems is the trees and shrubs we have here are not used to that, so the temperature of the soil was just killing plants off. We couldn’t do enough to keep things alive.”

Creating a balance between the use of evergreen and deciduous plantings helps Bonus provide an attractive outdoor environment for her customers year-round. “Some of the deciduous trees are absolutely wonderful, like the Japanese maples, which change colors throughout the year,” she says. “You really want to have a balance of that because they are so stunning. The evergreens will give you green all year-round. In the Northeast, you do a balance between those two.”

Bonus also balances perennials and annuals in her clients’ gardens, with an eye toward bloom times throughout the whole year. She likes using varieties of camellias that will bloom year-round. She also considers the durability of the containers she uses for the plants. “The wood planters are falling apart quickly,” she says. “I’m now using the powder-coated aluminum planters and fiberglass planters imported from England.”

Framing a view on a rooftop terrace is one of the specialties of Annette Bonus.

For most of the urban gardens that Bonus designs and installs, monthly maintenance is sufficient. “I’ve trained my customers that if there is a problem, they call me,” she says. “They know their gardens well-enough to know if something is not right. Some people are very particular about how they want their gardens to look and want maintenance every two weeks. For the most part, it’s monthly, and that includes fertilizing, pruning and doing whatever we need to do.”

Because a great deal of landscaping on urban patios utilizes containers, Bonus finds root pruning to be a challenge. “In [the] ground, a tree has a lot of room in which to spread its roots. When you put a birch or any kind of tree into a container, you only have so much room,” Bonus says. “The roots grow out laterally, hit the container wall, die off, and the tree starts to get less and less healthy.” She prunes them by cutting in 2 inches from the edge of the container and 18 inches down. “We take out all of the dead roots and pack it with compost and topsoil and drench it in a root saver liquid,” Bonus says. “Then you have another two to three years on that tree growth. You prune the top back in the spring of the following year, and you’ve basically got a new tree. Otherwise, you’re constantly having to dig out old trees and plant new ones.”

One of the benefits of urban container gardening is the ability to switch out plants and flowers and recreate a new look just by rearranging the containers.

Occasionally, Bonus will do a larger garden. One of the largest is a 1.5-acre courtyard in New York City situated between two streets and two buildings. “They were throwing out their leaves,” she says. “I got them to make a compost pile back there now.” Also in that particular garden, Bonus plans to release ladybugs and other natural predators. “It’s a challenge in the city not using pesticides,” she says, adding that pests found on the ground also find their way into roof gardens. “You’ll get all kinds of scale, beetles and horrible bugs that will attack your trees up on roofs. As soon as you put a garden 16 floors up, they arrive. A lot of people have children and don’t want you to spray anything on their garden, so that’s a challenge. That’s a challenge for everyone everywhere.”

Bonus sometimes hand-picks pests off of plants. To address scale, she’ll use a nontoxic dormant oil spray. When she must use pesticides, she contracts that work to another company since she is not licensed to apply them.

Going forward, Bonus plans to bring more services within her company’s offerings, with an emphasis on root pruning and fertilizing. “We’re going to do everything we possibly can,” she says. “The one area we’re not going to do is get into the irrigation area because the irrigation company I work with has huge insurance premiums because of the nature of it, the damage that can be done.”

She’s recently picked up more work by doing renovations on apartments that are for sale. “We’ll work with real estate brokers to spruce them up,” she says. “You can get more for an apartment that has an outdoor space as opposed to no outdoor space. If you invest $10,000 in a renovation of a nice-sized garden or terrace, you can expect to get most of it, if not double, back. It’s very worth it for the owners to put that money into it.”