An Old NYT article on Green Roof Gardening
- Subject: [cg] An Old NYT article on Green Roof Gardening
- From: Adam36055@aol.com
- Date: Sat, 28 Jun 2003 10:39:37 EDT
Hoping for a City Full of Farms on Rooftops
August 4, 2002
By ANNE RAVER
NEW YORKERS and other city people may be used to seeing
tomatoes and peppers in big pots on the roof, but what
about a little farm growing right out of the tar beach?
"This is our kitchen garden," said Leslie Hoffman, the
executive director of the Earth Pledge Foundation, a
nonprofit group that promotes sustainable agriculture and
environmental preservation. She crunched across the pebbly
ground of her vegetable plot, where tomatoes, eggplants,
sweet and hot peppers, lettuce and squash, to say nothing
of a river of herbs and flowers, are flourishing in a
strange soil mix covering about 700 square feet of the roof
of a 1902 town house at 149 East 38th Street in Manhattan.
She picked up a few of the smooth little pebbles. "This is
called expanded slate," she said. "It's like puffed stone."
The stones, formed by volcanic ash, do seem as light as
air, and they hold moisture. Mixed with 15 percent compost
and 30 percent sand, this porous soil (www.stalite.com,
phone 877-737-6284), has to be fertilized about once a
month. The fertilizer is fish emulsion, but not of the
"Most fish emulsion is rotten fish guts," Ms. Hoffman said.
"It's cooked, which kills the enzymes and proteins." This
fertilizer, not yet available commercially, is
cold-processed fish waste, alive with the enzymes from
By the look of the tomatoes ripening on the vines, these
plants seem to be thriving on fish and fake soil, with a
reservoir of rainwater beneath their roots. When rain is
scarce, a drip irrigation system is used.
"We had a bumper crop of arugula," Ms. Hoffman said. "And
zucchinis and yellow squash. I got six off the roof on
Heat-loving herbs and flowers - including basil, sage,
lavender, tarragon and verbena, bee balm, catmint, day
lilies - are flourishing among the vegetables.
Earth Pledge may be familiar to many, thanks to its virtual
farmers' market, www.farmtotable.org, which connects more
than 120 organic farmers and their fresh produce with
consumers looking for local foods, unusual recipes and the
latest events on food-related issues.
Last month, it began a Green Roof Initiative with a
conference of more than 100 people, from landscape
architects to investment bankers wanting to know how to
build greener, cooler, cleaner cities. Though Germans have
been growing green roofs for years, Portland, Ore., Toronto
and Chicago - which last summer installed a $1 million
green roof, covering half a block, on top of its city hall
- are leaders in North America.
Earth Pledge, which was founded in 1991 by Theodore W.
Kheel, the lawyer and labor mediator, to promote interest
in the principles of the 1992 Rio Earth Summit, hopes to
turn New York roofs into green oases that not only feed its
citizens but keep them cool.
Green roofs can combat the urban heat island effect, Ms.
Hoffman said. All the stone, brick and blacktop absorb so
much heat that cities are six to eight degrees hotter than
surrounding suburbs. Energy experts estimate that New York
could save as much as $16 million a year in energy costs by
growing green roofs, which not only cool buildings in
summer, but insulate them in winter.
Designed by Diana Balmori, a landscape architect based in
New Haven who also teaches environmental design at Yale
University, this green roof has an ingenious layered
construction, manufactured by American Hydrotech of Chicago
(www.hydrotechusa.com, 800-877-6125), which allows for the
absorption and retention of rainwater without leaking
through the roof. It also keeps roots from breaking through
the waterproof membrane that covers the deck.
The layering, from the deck up, begins with a seamless
waterproof membrane made of rubberized asphalt, which is
applied to the deck as a hot fluid. On top of that a root
barrier, polystyrene insulation, drain mat (resembling an
upside-down egg crate) for water retention and aeration and
finally, 3 to 12 inches of soil mix, depending on the crop,
like shallow-rooted mesclun, or deep-rooted tomatoes.
Ms. Hoffman said she does not know the actual cost of this
cutting-edge system, because most of the materials and
labor were donated. But American Hydrotech estimates that
the layered system, from waterproof mat to high-tech soil
mix, could cost $10 to $15 a foot, if you do it yourself;
$15 to $30 if it's a union job.
The Green Pledge garden has custom-made stainless steel
planters bordering two sides of the roof. These Cadillacs,
18 inches deep and lined with plastic foam for heat
insulation, form an elegant $20,000 wall around the roof.
They are filled with rosemary, oregano, summer savory,
cucumbers and pole beans winding themselves up steel posts,
which hint of trelliswork to come. (To see the green roof,
call the Earth Pledge Foundation at 212-725-6611 or visit
This green roof will collect about 75 percent of the water
that falls on it, Ms. Hoffman said. That means a lot less
water flowing into Manhattan's sewer system. "Most
down-spouts are connected to the same plumbing
infrastructure as toilets and sinks," Ms. Hoffman said. So
New York is treating all that rainwater the same as sewage.
What a waste. And when it rains in torrents, that water
floods the city's sewage system and can send raw sewage
straight into the rivers.
"Imagine a city of green roofs," she said. There wouldn't
be so much overflow. And all those air-conditioners
wouldn't be burning quite as much energy.
Earth Pledge is planning a fall conference for government
officials and others to draw up a plan for building more
green roofs in New York City. Ms. Hoffman has her own
vision for the redevelopment of the World Trade Center
site: kitchen gardens on all the roofs.
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