As the Urban Forestry intern, I recently had the opportunity to see the construction of the green roof atop the 11 story parking deck at the Cira Center South in Philadelphia. Jason Lubar, a Morris Arboretum Urban Forestry Consultant, was asked by the project’s green roof designer Roofmeadow, to assess the support systems for the planted trees. As the green roof is 11 stories up, the wind dynamics are more intense than at street level, and the trees need a flexible, but sturdy support system to properly establish.
Green roofs have come a long way, and are no longer just moss and sedums. Roofmeadow created a beautiful design at Cira that includes:
- A grassy lawn with a small hill
- A meadow with tall grass such as prairie dropseed, reed grass, big bluestem and perennials such as liatris, veronica, pinks, beards tongue and alliums
- Several trees including honey locusts, swamp white oaks and redbuds
- Walkways and plaza of permeable paving
- A rainwater storage system that will direct rainwater into the lawns and gardens and will mitigate the first couple of inches of rain.