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Oct. 31, 2012: The green roof, no worse for wear, after Hurricane Sandy. Rather than growing in soil, which can clog drainage systems and is heavy when wet, the plants sit in a 4-inch layer of a growing medium made up of gravel and organic matter.
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Nov. 8, 2012: 238 Thompson after an unusual autumn snowfall.
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Aug. 2012: Some amount of browning in the late summer is normal, Reis says. The green roof is not irrigated, and the plants receive supplemental watering just 3-4 times a year. “Otherwise,” Reis says, “the plants are on their own.”
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The rooftop of 238 Thompson in bloom.
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New green roofs are especially susceptible to weeds, so they require a significant amount of maintenance over the first 2-3 years.
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Chives aren’t just for potatoes anymore. A New York native that sprouts purple blossoms in the spring, it’s among a handful of edible plants growing atop 238 Thompson. (Others include Corsican violets and creeping thyme.)
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May 2012: Native perennials tend to attract pollinators, Reis says—a goal that’s become urgent with growing concern over the collapse of bee colonies. But Reis has yet to capture the insects on film: “One of the guys told me he was up there the other day and it was just flooded with butterflies,” he says. “I missed that.”
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Oak sedge, which some gardeners have advocated as an eco-friendly lawn substitute, thrives on this green roof.
It’s not heaven, but it’s close: As students gather to pray and meditate below, the plants of the Edenic green roof atop NYU’s Center for Spiritual Life reach skyward, kissed by bees and butterflies.
While most green roofs primarily feature sedums, hardy succulents valued for their ability to hold water, George Reis, NYU’s supervisor of sustainable landscaping, brought variety to the 3,700 square foot sky plot at 238 Thompson, mixing in native plants like primrose and wild columbine when the roof was planted in fall 2011. He and his team visit the rooftop weekly, maintaining some 3,000 plants without the use of herbicides, fungicides, or insecticides. Nearby, the School of Law operates another green roof at Wilf Hall.
“One advantage of using native perennials is that they have different looks in all seasons—sedum roofs tend to be more static,” Reis says. To catch a glimpse of goldenrods blooming this fall, head to the upper floors of the neighboring Kimmel Center and look west.
While not quite barred by pearly gates, the roof at 238 Thompson isn’t open to the public—so from his perch high above Washington Square, Reis is in a unique position to watch flora transform with the seasons, both on the roof and beyond.
“I like to take pictures from there because it creates the illusion that the green roof is an extension of the park,” Reis says. A handful of his choice shots, captured between April and November 2012, appear above.