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STORY BY OryANA ANGELgreen growTHE CITIESANDREW GREGORYAmid the buzz and the grind of our biggest metropolises,more and more sky gardens are beginning to bloom.The secret garden. An aerial shotreveals the sprawling elegance ofM Central’s rooftop. This green spacein the Sydney suburb of Pyrmont hasbeen growing strong since 2005.62 A u s t r a l i a n G e o g r a p h i cMay –Ju n e 2 0 1 463

A cut above.The garden abovethe loft-style MCentral apartmentsin Sydney has amodern design, buta simple, downto-earth feel.oryana angel isa former AustralianGeographicstaff writer, whoalso workedas an associateproducer on AG’sBest of Australiadocumentary series.Iam in Sydney’s Pyrmont, one of thenation’s most densely populated suburbs.Here, four lanes of Harris Street meet theoverpass for the Western Distributor freeway and the Cross City Tunnel. This is oneof the b usiest thoroughfares in Australia, yet I amstrolling around a peaceful oasis. It’s a spacious garden about half the size of a rugby field, but it’s notwhere you’d expect it to be. We are six storeys highon the roof of a heritage-listed residential buildingcalled M Central.“It’s an island in the sky,” says Daniel Baffsky, principal at 360º Landscape Architects, who designed the2600sq.m communal space. “In an intense urbanenvironment people need a place to be immersedin nature.” The garden was influenced by Brazilianmodernism, but its gentle water feature, woodenwalkways and swaying pennisetum native grass makeit feel minimalist to me. It’s a little Japanese, reminiscent of Berlin and, oh, so Sydney.“I’m happy to see it looking so good,” says Daniel,who hasn’t visited the garden for about three years.He is pleased that, without his supervision, it isblooming. “To survive on a rooftop, plants need tobe hardy and low maintenance – bulletproof.”Exposure to harsh sun, little natural shade anda lot of wind mean that rooftops can be hostile64 A u s t r a l i a n G e o g r a p h i ce nvironments. This one has a range of native speciesand succulents, a mix that clearly works. The gardenwas retrofitted onto the existing building in 2005 andthe only damage to the ground cover appears to befrom frolicking dogs. While I’m in the garden, twoof the 400-plus people living in the building arriveto walk their pooches.We talk with Mina Choi, who brings her tiny whiteshih tzu-maltese terrier here to stretch its legs fouror five times a day. “We take her up here early inthe morning, after breakfast, at lunch, before dinnerand at night,” says Mina, 35, who bought the apartment with her husband in 2010, largely because ofthe pet-friendly rooftop garden. “It’s a nice place towalk the dog. There’s a great view.”Children and other families living in the buildingalso enjoy the rooftop sanctuary. On the far westernside there’s a softball court, paths to ride scooters,deck chairs, barbecue facilities, a huge communitycentre and more great views to boot.ALTHOUGH AUSTRALIA lacksthe rooftop- garden and green-roof culture that’s becomedeep-rooted in Europe and North America, green roofs are gradually creeping across our biggest cities. The City of Sydney (from Newtownand Annandale in the west, to Elizabeth Bay andFROM TOP: COURTESY 360º LANDSCAPE ARCHITECTS; SHHighrise meadow.A dragon’s bloodtree and billowingpennisetum grassflank the walkwaysof the M Centralrooftop garden.SCOTT HAWKINS (SH); Dracaena cinnabari; Pennisetum setaceum“The garden is flourishingbut also the gardenersare flourishing.”Rosebery in the east) has more than 96,000sq.mof green walls and roofs. This includes more than50 green roofs and 25-plus green walls, and thecouncil receives a new development applicationevery week. In central Melbourne, the movementhas progressed even further, and there are about100 green roofs, 50 green walls and hundreds ofgreen facades.The City of Sydney council’s senior project officer for green roofs and walls, Lucy Sharman, saysinterest has spiked in the past 18 months. “Thecity is becoming more densely populated. Almostthree-quarters of residents are living in high-riseapartments – people are keen to be around greenery.”University of Melbourne senior lecturer in urbanhorticulture John Rayner says there’s no shortageof research pointing to the social and psychologicalbenefits of access to green spaces in the city.“People like them; it adds to the green open spacenot available at ground level. [They] are healthier,happier and take less sick days simply because theyare looking out at a green roof that could cost only 250 a square metre.”One rooftop garden spreading happiness is thevegetable patch that thrives atop the Wayside Chapelin Potts Point, on the fringes of the Kings Cross redlight district. From there, looking over a curtain ofpiquantly scented wild passionfruit, I see the SydneyCBD skyline punctuated by skyscrapers and SydneyTower. In the other direction is another rooftop garden on Macleay Street. Otherwise, there are just awhole lot of empty rooftops and tired air-conditionersystems rattling away in the heat.During my visit to this drop-in centre for thehomeless, mentally ill, addicts and other downand-outs, it’s hard to know who is a visitor and who isa volunteer – everyone seems to be buzzing around,empowered by their role in the project.Rick ‘Pee Wee’ Geoff, 77, strides p urposefullyamong the organic eggplant, tomato, warrigalGardens givingback. WaysideChapel’s programmanager WendySuma (above, at left)admires the fruits ofher labour with JonKingston, who holdsgardening classes atthe chapel. Pee Wee(left), a regular visitorto the garden, tendshis pillow plant.May –Ju n e 2 0 1 465

Green high-tech.One Central Parkproject director MickCaddey (above). Thepanels track the sunand bounce lightfrom the east tower‘s29th floor down tothe retail atrium andcourtyards. A Sydneybusinessman (aboveright) passes thebuilding’s street-levelvertical gardens.greens, finger limes and native mint. His job is towater the plants and he lingers at his favourite – thecurry plant. “I love my pillow plant,” he says of thesoft, silver-hued herb, which I find to be pleasinglysoft when I’m prompted to cuddle it. “I like participating. As long as they need me, I’ll keep coming.There’s nowhere else I can come like this.”The rooftop vegie garden was brought to life twoyears ago by Wayside program manager Wendy Sumawho wanted to create a green space for disadvantagedpeople and locals to share. “The garden is flourishingbut also the gardeners are flourishing,” she says.Wayside’s produce gets put to good use, supplyingthe third floor for cooking lessons and then it’s servedup in the bustling ground-floor cafe. There are alsotwo large beehives, home to some 180,000 bees, andan efficient compost system, which ensures the plantsget the nutrients they need.AS CITIES GROW warmer because of climatechange, green roofs and walls can relieve stifling urban conditions. Concrete andasphalt absorb much more radiation than foliage,resulting in more energy required for air c onditioning.And heat-related illness is becoming more common.“There are many more air conditioners running inurban areas than we had a decade ago. The costs inenergy and latent heat produced are enormous,” Johnsays. “Other ways of cooling are becoming a necessity,not a luxury.”The thermal benefits of an irrigated green roof can66 A u s t r a l i a n G e o g r a p h i cmean significant energy savings. By providing shadeand insulation, such roofs keep buildings warm inwinter and cool in summer. A 2009 joint Universityof Melbourne and CSIRO study found that greenroofs can reduce cooling costs by as much as 50 percent, compared with a conventional concrete andbitumen roof.Another reason many cities are investing in greenroofs is to help cope with stormwater. “A deep, greenroof, with a large surface area and lots of plants andsoil, can absorb up to 80 per cent of rainfall that fallson it,” John says. “Even a shallow green roof, 10cmdeep, can hold 50 per cent of the rainfall.”Following the disastrous flooding in the wake ofHurricane Sandy in 2012, New York City – with itsabundance of hard concrete surfaces – is now investing in parks and green roofs. These act like giantsponges to soak up stormwater run-off.It’s not only green roofs causing a stir around theworld. Green facades, vertical gardens and climbingplants can have an even greater environmental impacton a high-rise building due to the sheer amount ofspace available for coverage. A study conducted inSpain in 2011 looked at the effects of green facadeson a building surface and its ambient temperatures.It showed that, during summer, buildings with a wallcovered by a climbing plant were up to 15 degreescooler than those without.In Chippendale, in Sydney’s inner west, a futuristic 2 billion development can be found on the formerCarlton and United brewery site. Continued page 70BOTH PAGES: SHBuildings with a wall coveredby a climbing plant were upto 15 degrees cooler.Foliage cascade.Nutrient-enriched recycledwater sustains OneCentral Park’s garden.May –Ju n e 2 0 1 467

islands in the skyWith the structural integrity of the building at stake, a rooftopgarden must be functional, as well as pleasing to the eye.wildlifeRooftops can hostwildlife that doesn’t usuallythrive in urban spaces. Recreate features of native habitatsso that migrating birds can use thegardens as stepping stones alonggreen corridors, which are otherwisedisrupted by urban structures.Insect ‘hotels’ and rockeriesprovide shelters forinvertebrates.rainwater tanksRainwater cisterns cancollect water, which canbe used to irrigate agreen roof. Water canalso be filtered and pipedinto the building to beused in showers, toiletcisterns and sinks.greenhousesGreenhouses can be technologyhotspots: they can house‘aquaponic’ systems, where fishare raised in tanks, and theirwaste is used as fertiliser. They canalso be used to heat buildings:they trap solar energy during theday, and with an energy-exchangesystem, this can be transferredinto the building.drainageThis keeps rooftopspuddle-free and preventsplant roots from becomingwaterlogged. There are twoconsiderations: within the gardenprofile (addressed by a drainagelayer), and on the roof structure.Drainage is achieved withgutters, cut-outs at theedge and internalpipes.irrigationThere are a varietyof irrigation methodsto keep roofs lush. Driphoses can be laid atop yourgrowing substrate, or layeredbeneath to keep moisture in directcontact with roots. A drainagelayer can be installed, whichretains some water, whileletting the excessrun out.layersGreen roofshave several layers: aroot-resistant waterproofingmembrane, with a root-repellingchemical or copper foil to protect thestructure below; a barrier shieldingthe membrane; a drainage layer toallow excess water to escape; anda filter layer separating thedrainage layer from thevegetation.A patch of your own1 Think about the local climate. Annualperiods of drought or heavy rain can limitwhich plants can succeed on your roof. Rememberthat the sunlight will be more severe on yourrooftop than in your backyard, so plants that dowell at ground level might not be tolerant of arooftop habitat.Solar panelsSince rooftops are exposed toample sunlight, they are theperfect place to install solarpanels. If the electricity generatedexceeds the building’s needs, thisexcess energy can often be soldback into the grid for profit.2 Consider nearby buildings that could affectthe microclimate. Check for structures that maycast shade over your roof or reflective facadesthat could direct concentrated heat towards yourplants. Adjacent rain gutters and eaves could flushsurges of water onto your roof during a storm.3 There are two types of roof garden,based on soil depth: intensive (layer of 15cm ormore) and extensive (shallow layer of 5–15cm).Composed of a layer of thin, lightweightsubstrate, extensive gardens can support grassesand succulents and are ideal if you want a lowmaintenance option. Intensivegardens are more complex andrequire more attention.4 Planting SEVERAL specieswill make your garden moreresistant to occasional stress andplacing individual plants at thehighest possible density willprevent weeds from colonising.5 If your roof is on a tallbuilding, wind can be a concern.High winds can uproot plants anderode your growing medium.communal spacesGreen roofs are ideal meeting placesfor community events and can offera variety of recreational activities,including playgrounds, walking paths,swimming pools, barbecues and evenopen-air cinemas.educationRoof gardens canbe used by schools toteach about environmentalsustainability, ‘green’building designs and theimportance of nativewildlife habitatin cities.68 A u s t r a l i a n G e o g r a p h i cnative plantsIt’s best to plant native species: they are adapted tothe environment and can often survive with naturalrainfall, lessening irrigation demands. Mimickingnative plant communities also lessens maintenance.waterproofingThis is essential toprevent water leakage.Since tiny leaks are difficultto locate, a leak-detectionlayer (incorporatingelectrical conductivity)is a must.courtesy NL ARCHITECTSsoilThis is a factory blend or a custom growing substrate– ideally a mix of native soil with organic and mineralmaterial, such as humus, wood chips, lava and clay.The blend is determined by the needs of the plants. Thesubstrate must retain water without preventing drainage,and must be able to support the plants’ root systems.water featuresPeople are often wary of installing pools on rooftops, butwith prior structural considerations, this can be a viableoption. A pond with aquatic plants can be created, as canan ephemeral stream that fills and empties when it rains.weightBuildings areassessed by expertsat the design stagelong before gardens areinstalled. Green roofs add asignificant weight burden,which increases withmoisture.rooftop farmingIn urban areas, rooftopsoffer plenty of space andsunshine to plant vegetablegardens. Local foodproduction is an eco-friendl