If you want to understand the potential of living roofs, pop by the public rooftop gardens at Chicago Botanic Center’s Rice Plant Conservation Science Center.
“Almost anytime you go up there, you’re going to see something cool,” said Richard Hawke, who manages the plant science center.
Rice Plant Conservation Science Center green roof. Photo courtesy of Chicago Botanic Center
Hawke credits former Mayor Richard M. Daley for kick-starting the area's green-roof movement in 2001 with a groundbreaking project that covered 20,300 square feet of Chicago City Hall with more than 150 varieties of plants. The green roof saves the city about $5,000 on utility bills and can keep the roof temperature up to 80 degrees cooler than nearby buildings with black roofs.
Chicago now claims more than 350 buildings and businesses with sky-high prairies, gardens and vegetable plots averaging 5,234 square feet each and collectively covering close to 5.5 million square feet, according to city statistics.
While many are private and set up for economic and environmental incentives, Hawke sees green roofs evolving to be more social and interactive as businesses use the gardens as gathering spaces and to enjoy nature or to use the area for harvests.
“That’s a fairly new trend,” Hawke said. “It’s going to get stronger and stronger.”
Here’s a look at some of Chicago’s most inspirational green roofs:
1. Rice Plant Conservation Science Center
Doubling as a living laboratory, this Chicago Botanic Garden complex in Glencoe includes 16,000 square feet of rooftop gardens with soil depth of four to eight inches. Roof Garden South, which features a natural prairie-like setting with native plants, bursts with color in early June with orange butterfly weed, lavender, white pestemon and pink roses.
Roof Garden South. Photo courtesy of Chicago Botanic Garden
Green Roof Garden North feels like a more traditional, organized flower garden that fills with bulbs and moss phlox flowers in early spring and waves of other flowers throughout the season.
Roof Garden North. Photo courtesy of Chicago Botanic Center
2. McCormick Place
Chicago Botanic Garden’s Windy City Harvest Urban Agriculture Program plants a 2.5-acre green roof on North America’s largest convention center. The McCormick Place gardens produce 8,000 pounds of herbs and vegetables (beets, peppers, lettuce, carrots and more) that are served at the convention center through caterers and restaurants. As a bonus, 20,000 honeybees produce 50 pounds of honey a year. The rooftop is open occasionally to the public for special events and tours.
3. Millennium Park
This internationally popular and interactive park, which opened in 2004, ranks among the largest green roofs in the world at 24.5 acres. Visitors to park highlights such as the J. Pritzker Pavilion, Lurie Garden and Cloud Gate sculpture may not realize the park is a green roof because it’s at ground level, but it was constructed over parking garages and a rail yard.
Lurie Garden in Millennium Park
4. Soldier Field
The home of the Chicago Bears transformed the roof of its four-story parking garage into a 5.5-acre rooftop park and earned awards for its energy-efficiency efforts.
Your Own Living Roof
Anyone inspired to consider a smaller-scale green roof can tap Chicago’s Midwestern expertise—especially in choosing plants that can handle extreme seasonal temperatures and higher winds found on rooftops. Other considerations include: finding out if a roof can handle additional weight, pursuing any permits or licenses for the project, and finding specialists in roof access and safety, irrigation, planting materials and the ideal depth.
The city of Chicago put together this starter guide.
The website greenroofs.com also provides resources, supplies and contractors that can be searched by city and state.