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Mar 2011  |  By Laura Hine  |  Comments

Green Roofs Offer More than Color

After you’ve seen the living, growing roof at the Daniel F. and Ada L. Rice Plant Conservation Science Center at the Chicago Botanic Garden (CBG), you’ll never be satisfied with your asphalt, tile or slate roof again.

This flat roof is covered in color and life—40,000 plants comprising 200 different species, including sedums, cacti, asters and creeping phlox.

But this roof, which is open to the public, is more than a gorgeous place to watch a sunset; it has huge environmental benefits, like reducing storm water runoff and energy use in the summer and winter.

According to Greg Mueller, Ph.D., vice president for science and academic programs for the CBG, green roofs can also help mitigate the heat island effect that happens in dense areas, all while providing a habitat for birds, bees and other pollinators. On top of these benefits, it actually lasts longer than a traditional roof.

But this isn’t a weekend DIY project.

Richard Hawke, plant evaluation manager, notes that even though the soil isn’t deep on the roof—it ranges from 4 to 8 inches—it still adds a lot of weight, making it easiest to plan for a green roof with a new building.

Still, the whole roof doesn’t need to be planted to get some of the benefits. In a downtown condominium complex, Aaron Zych, senior project manager for ILT Vignocchi Inc., installed perimeter planters, which were deep enough for Amur Maple trees, small evergreens and perennials.

“It’s important to choose tough plants,” he notes. The same plant that’s baking in the summer sun is going to be whipped by frigid winds. The Japanese Maples didn’t make it, but the daylilies thrived.

So why add plants to a roof? One of Zych’s clients hated staring at a black tar roof and wanted a beautiful space that could be enjoyed. For the CBG, the green roof is about being an environmental leader.

“We’re a living laboratory,” says Hawke. And he notes that their roof is the largest suitability trial of roof plants in the country: “The more diverse plants we can test, the better.” And the more green roofs that are inspired by these beautiful spaces, the better for all of us.

The roof garden is open to the public when the Chicago Botanic Garden is open. Learn more on their website at chicagobotanic.org.