Rooftop gardens: the coolest roofs around

By Emily Loewinger

Rooftop gardens and green roofs are beginning to pop up in urban areas. One of the most well-known rooftop gardens towers over Chicago at the Chicago City Hall. Aside from looking pretty, green roofs purify the air, moderate indoor temperatures, provide a longer roof lifespan and can even be used as a food source.

A rooftop garden in Naples, Florida, designed by plant physiological ecologist Brian Bovard, blooms in the sunlight. This pictured garden is dry soil; Bovard and other ecologists have been working with wetland gardens for this particular roof as well. (Photo by Brian Bovard)

There are many different ways to go about installing a rooftop garden. The methods of design are directly dependent on the style and structure of the roof. On flat roofs that are not shingled (like balcony roofs), it could be as simple as adding potted plants or wooden plant beds, or as complicated as structuring rock beds and sectioned off gardens like in the roof pictured above. With shingled roofs, the weight of the garden will determine whether the roof is eligible for a garden, however it is still possible to turn a shingled roof into a garden.

These roofs are especially beneficial in Florida because they aid in natural cooling. This means lower electricity bills and more money kept in your pocket.

“It’s an added insulation, so less heat gets in and less energy escapes the house,” Florida Gulf Coast University professor and plant ecologist Brian Bovard said.

Bovard has been working on installing a rooftop garden on a home in Naples. “From data we collected in Naples, we were looking at shifts that were in the order of over 90 to 100 percent difference [in temperature].”

For this project, Bovard has been working with native species of both wetland and xeric (dry soil) plants. Both have been successful on the Naples rooftop so far, he says.

The gardens, especially the xeric ones, are easy to make and can be installed in as little as one week. The physical structure of the house plays a large role in the timespan, efficiency and cost of the garden.

Rooftop gardens on flat roofs are the easiest, cheapest and quickest. They project requires only pots, soil and plants. Curved or slanted roofs require more time and configuration. These types of roofs generally require that a structural engineer examine the sturdiness of the roof because the addition of weight from the potted plants could damage it.

A well-camouflaged Swallowtail caterpillar made a cocoon on this Parsley plant. Parsley is often used in sustainable herb gardens on rooftops because it grows without needing much maintenance. (Photo by Emily Loewinger)

The other potential downside of green roofs is the initial cost. They’re generally twice as much money as a traditional roof, or about $30 to $100 per square foot. however, according to Bovard, the lifespan of the roof is usually about two to three times longer than a traditional roof. “So, with the lifespan of the roof it’s going to cost you less. In addition, you’re going to get energy savings by having a rooftop garden,” he said.

Rooftop gardens are also beneficial for the environment. During photosynthesis, they pull carbon dioxide from the air and turn it into oxygen. They also reduce pollution by catching stormwater runoff and they are habits for wildlife.

“I think green roofs are a phenomenal idea and have incredible benefits for homes and the environment,” senior marine science major at FGCU, Brooke Loney, said. “Ideally, this would become a normal trend in cities in the near future.”