The urban cool of rooftop gardening can easily transfer to smaller cities and rural areas as well.
“Creating a green roof or a roof garden is a great way to utilize space that you already have,” says Corbett Miller, horticulturist at Taltree Arboretum and Gardens in Valparaiso.
From the simplistic—potted plants and containers brimming with blooms—to sophisticated seating arrangements, walking paths and plantings, these gardens create more outdoor living spaces or, at the least, turning the top of a small outbuilding such as a garden shed or even a dog house, into a visual focal point that becomes another part of an eye catching garden design.
But, for those of us new to the concept, there’s a distinction between green roofs and rooftop gardens.
“For a green roof, think of it as more like a prairie transported to the top of you building, something solidly planted sometimes with pathways,” says Allan Smessaert, Owner and General Manager at Acorn Markets based in Kankakee, who has created rooftop gardens in Northwest Indiana. “Rooftop gardens are more like a living space with no hardscape. It’s more about the seating with built in and portable container.”
At Taltree, one of only eight arboretums in the world to be awarded Level III accreditation by The ArbNet Arboretum Accreditation Program sponsored and coordinated by The Morton Arboretum in Lisle, Illinois, they’ve created a green roof in their Adventure Garden using a preexisting roof structure to harbor species of plants tolerant of weather conditions like high heat and low water. For this particular roof, three varieties of sedum were planted in a diamond shape central design because this hardy perennial, with its thick, fleshy leaves retains water, tolerates both intense sun and periods of drought, requires little to no maintenance and upkeep and look as good in fall as they do in the spring.
Other plants that work well when designing a rooftop garden are hardy daylilies, ajuga—which is good for attracting butterflies and ornamental grasses like Blue Fescue and Maidengrass.
“In the city everyone has a rooftop garden because they don’t have any other space,” says Ann Marischen, owner of Flower Power Gardens and Chicago Mayor Daley's Landscape Award winner in both 2000 and 2001, who created many roof top gardens in Chicago.
Marischen, who moved from Chicago to Valparaiso over a decade ago, is currently creating a 60-foot-long by 30-foot-wide rooftop garden atop of a converted commercial building that is now a residence in Valparaiso.
“We’re looking a maybe adding a pergola as well as some big planters for trees,” say Marischen, who also creates containers with evergreens, shrubs, grasses and perennials as well - for year-round beauty. “We’ll have seating areas and lounging areas and maybe, because of upkeep, artificial turf.”
Smessaert says sees rooftop gardening as not much more difficult than land gardening except for technical issues.
“You need to consult with an engineer or architect to see how much load an area can hold,” he says noting that dirt adds a lot of weight to a rooftop. “And you have to watch everything you add to the garden because it really adds up. I have an eight foot container that’s eight foot tall and looks like aged copper but it’s not. Those types of containers are perfect for rooftop gardens.
Though flat roofs lend themselves more easily to creating an up top garden, Smessaert says that even pitched roofs can be garden-able.
“They do it a lot in Europe and some even have goats grazing on them,” he says. “And if you just want to have a green roof for energy savings, it’s very doable as long as it’s not too high of a pitch. What is important is that it’s planted heavily and the roots are holding, like you find on a hillside.”
Maddie Grimm, Director of Education at Taltree, says that gardens on top of roofs are a great place to show gardening techniques that are both simple and aesthetically pleasing. She notes that besides being attractive some of the other benefits of a green roof and/or roof garden include an increased lifespan of roofing materials because there’s less erosion and weather damage and the gardens provide insulation by keeping hot sun from affecting inside room temperature in summer and decreasing heat loss through the roof in winter.
Public buildings are also adding rooftop and green roof gardens as both places to gather and to enhance the view.
Bill Hutton of the fifth generation Hammond based Hutton and Hutton Architects and Engineers says that when they worked on the design of the Hammond Academy of Science and Technology (HAST), they look at outdoor areas and rooftop gardens as a place for students to study and meet.
“We developed the concept of having several areas with seating and plantings,” he says.
A rooftop garden was also part of the design when planning the North West Indiana Veteran Village in Gary which provides supportive housing as well as other facilities for veterans.
Smessaert, who has designed rooftop gardens in New York where the weather is milder, says that Chicago and Northwest Indiana have more severe weather and the cold and the wind are more intense up on the roof which needs to be taken into consideration when landscaping.
“It’s a whole other world up there,” says Marischen about rooftop gardens. “You really have to make sure everything is weighted down. In the summer it’s very hot, very dry and all year round it’s very windy. It’s easier to take care of a ground garden but rooftop gardens can be so distinctive and so special.”