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Whatsapp The highest vertical gardens in the world are attached to the new Central Park development in Sydney.

Across the towns and cities of Australia, vertical gardening is gaining popularity, with a new development in Sydney featuring the world’s tallest gardens. As Ann Jones discovers, employers and town planners are using these green walls to capitalise on biophilia–our innate attraction to plants and the natural world.

It’s before dawn and the sounds of the city are dampened by low level cloud. A silent lift shoots up more than 100m to a concrete staircase and a door that opens onto another world. Thirty-two storeys up, a team of extreme horticulturalists is about to engage in high altitude gardening.

Below them, Sydney wakes up. As the dark sky and bright lights trade roles, the gardeners use pneumatic staple guns, felt and PVC to tend the tallest vertical gardens in the world.

It's very similar to other types of gardening, except here you're hanging thirty floors in the air sometimes.

Across town, in a bitumen-filled council depot, a very happy woman stands next to a small patch of green. She is Lucy Sharman, the City of Sydney Council’s green roofs and walls project officer. Her green wall is made out of glorified milk crates, with pots of soil and plastic irrigation pipes running behind a layer of foliage.

‘Maybe it’s a bit twee, but it makes me smile going past things like this, where it’s so lush and green in amongst a pretty inhospitable depot really,’ says Ms Sharman.

The sense of calm that washes over Ms Sharman may not only be due to professional pride. It may be the effect of biophilia. The biophilia hypothesis holds that people have an innate attraction to plants and the natural world. It’s a theory that employers have adopted in an effort to reduce absenteeism and increase productivity in the workplace. Jock Gammon, the director of Junglefy, creates green walls for clients around Australia. ‘One client we have is a call centre and they have a high staff turnover,’ says Mr Gammon. ‘The cost to train up new staff is very expensive, so they’ve invested in green walls and games breakout areas.’

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However, the case for biophilia is not clear cut–several researchers have noted that the presence of living things might be an annoyance to some, or that the effects may be broadly positive, but specifically unclear in either cause or result. Researchers at Deakin University in Victoria have noted that despite a general consensus on the broad positive affect of contact with nature, it is yet to be integrated into the public health system. This may be because, as Bjørn Grinde and Grete Grindal Patil wrote in the International Journal of Environmental Research and Public Health, biophilia is ‘probably not an attribute with a strong penetrance’. According to their research, the relationship between humans and plants is likely to be shaped to a large extent by cultural factors and individual peculiarities.

So how does such a subtle relationship get translated into the economics that rule development in our cities? One of the problems faced by the City of Sydney Council in promoting the greening of the city in accordance with the Sustainable Sydney 2030 plan is proving a cost/benefit relationship for green walls and roofs.

‘I’m very confident that these actually make you feel better, but [we need] some solid evidence and really, it’s solid economic evidence, to say you put a $100,000 green roof on a building and you will get x kind of dollars return in terms of mental and physical health and wellbeing,’ says Ms Sharman. ‘We need more evidence in that area and it’s a bit tricky, but we’re getting there.’

The $2 billion Central Park development in Sydney’s Chippendale, right on the edge of the CBD, has banked on the attractiveness and ultimately the profitability of its green credentials in the real estate market. The development is still being built and when completed will cover a six hectare site. Frasers Property CEO Guy Pahor recently said Central Park was on target to be one of Australia’s ‘greenest and most self-sufficient mixed-use urban developments’, having incorporated sustainability and environmental stewardship as fundamental principles of its planning. Mr Gammon’s company is responsible for the green walls on the part of the development known as One Central Park.

Green walls of Sydney (Courtesy City of Sydney Council)

‘The scale of One Central Park is unlike any others in the world,’ he says. ‘It’s actually the highest green wall in the world, and at time of design it was the largest at 1200m2, but that’s just unfortunately been eclipsed by a project in Singapore at 5000m2.’

The walls were designed by Patrick Blanc, whose technical specifications and sweeping aesthetic mark some of the larger and more prominent green walls across the world. There are three layers to Mr Blanc’s green wall system; one of PVC and two of specialised felt. The outermost felt layer has little pockets cut into it, into which seedlings are placed and secured by staples. The plants are sown in swooping lines, like large brush strokes of foliage across a canvas. Contrasting colours and textures are only one of the criteria for plant selection: they must be able to withstand high winds, and must all have the same sun and watering requirements.

The irrigation of the seven kilometres of planter boxes and green walls at One Central Park is fed by four pumps concealed in a room deep in a basement level. The pumps are the heartbeat of the garden, and the green walls rely on irrigation drippers placed at four metre intervals.

‘At the top the drippers are 20 gallons an hour and lower down there 12 litres an hour, so we have good control at getting a wetting,’ says Mr Gammon. ‘It’s a hydrophilic fabric, so the moisture moves through it very nicely. It has nutrients in the water and those nutrients make their way through the felt. We’ve currently got it set at five times a day.’

Andrew Wands, who leads the teams that tend the walls and roof gardens, says it’s very similar to other types of gardening, ‘except here you’re hanging thirty floors in the air sometimes’.

Just like in normal gardens, some plants do better than others, and the technical aspects of the project have been refined over time. Early on in the establishment of the vertical gardens an irrigation pipe was mistakenly cut by a tradesperson, leading to the death of a large patch of plants.

‘There were obviously teething problems, because no one has ever used this system before on such a grand scale,’ says Mr Wands. ‘We have to be very eagle-eyed to make sure that everything is being watered. But in the future I don’t think there’ll be a problem; we’ve got it ironed out now.’

One of the beautiful things about green walls, says Ms Sharman from the City of Sydney Council, is that they can take so many forms. ‘They can be anything from sticking a plant in the ground and growing a vine up it, so passionfruit for example, that’s also considered vertical greening. Or these really extensive felt matting that’s attached to the wall as well,’ she says. ‘Probably one of the most common ones is really just buckets of dirt attached to the wall. It really doesn’t matter if you’ve got an expensive art piece of growing plants or you’ve just put something in the ground and grown it up – as far as I’m concerned, if it’s got chlorophyll in it, it’s a green wall.’

The walls, according to research compiled by Ms Sharman, clean the air, provide insulation for the inside of the building, counteract the ‘urban heat island effect’, and increase biodiversity. As the outdoor vertical walls become established, microclimates occur between the plants, and mosses, liverworts and weeds appear. The walls can attract bees and insects, and later larger animals, such as lizards. There are even reports of birds nesting in Mr Blanc’s walls overseas.

So, if there are inexpensive models, and there are broad positive effects to health, biodiversity, climate, air quality and building temperature control, what is holding people back? Ms Sharman says her surveys have found that people are worried about the gardens making their buildings leak. ‘Green roofs actually protect the waterproofing layer. You can get a good 20, 30 or 40 years more life out of your roof because it is protected from sun exposure and wind exposure,’ she says. ‘But there is still a perception that it is an issue, and when we dug a bit further we found that waterproofing is a bit of an issue in Australia full stop–the industry standards are really very basic and it’s actually not the green roof or wall, it’s the way that you install the waterproofing that is the issue.’

Back at Central Park, a water droplet falls to the pavement after making its way down metres of plant panelling, past small ferns, begonias and mosses. It plops to the ground and narrowly misses an enthralled pedestrian. The pedestrian is standing close to the wall, hand outstretched, touching the plants and peering up to see just how high the garden goes. The gardeners say they have to replace these plants at ground level quite often, because of the constant touching from passers-by, who can’t help but reach out a hand to see if the plants are real.

‘It definitely brings some nature to the city, and I think that’s why everyone likes it, and everyone needs it as well–a bit of open space, a bit of green, a little bit of nature,’ says Mr Wands as he staples another plant to the wall.

Find out more at Off Track. Hear about the future of greenery in the city at Life Matters.