10 July 2014 — French artist and botanist Patrick Blanc was in Sydney this week to check on the progress of the now iconic vertical gardens at Frasers and Sekisui House’s One Central Park, and to provide some insight into how the gardens were developed.
The green walls, which feature 35,200 plants from 383 native and exotic species and cover 1200 square metres, are Blanc’s highest-ever vertical gardens with two of the 21 panels reaching a height of 116 metres. A water recycling plant in the basement of the building generates around one million litres of water a day, providing all of the irrigation requirements of the green walls and surrounding parkland. The garden’s dripper irrigation system changes frequency of runs depending on the season, and can be remotely controlled to increase or decrease water cycles as needed.
Diversity is crucial
Blanc said diversity of plants was one of the most important considerations for vertical gardens when taking into account dry spells and strong winds, both factors in Sydney’s climate.
For example, he said, an incident where there was water was cut off to one panel caused some plant death, but because there were around 30 different species the hardier ones had survived.
“The higher the diversity of plants you have, the less problems,” he said. “Always to have high diversity is very important, both for disease and for accidents.”
Aesthetically too, it looked more artistic with a higher diversity of plants.
Climate change was another factor that need to be taken into account when choosing plants, Blanc said. He noted that during a visit to Singapore, there was a huge number of fern species that had died due to an exceptionally dry season, with increasing strength of El Niño a factor.
The climate in Sydney was “easy” compared to places like Singapore, Berlin, London and New York, he said, however Sydney’s strong, regular winds were difficult to work with. When you have panels at more than 100 metres high, the plants need some form of sheltering, and strong species must be chosen, he said.
“You just have to know which plants for the top, which for the middle and which for the bottom.”
The plants Blanc has chosen to withstand seasonal conditions include at the top of the wall, a selection of plants that can handle a lot of sun and wind, including acacia and grasses, while more delicate plants requiring shading and more hydration, such as goodenia and viola, are used at the bottom, along with many ferns.
Pointing to the “ugly” UTS Tower, Blanc noted that it itself was a form of nature – with the concrete casing made of limestone. And like other limestone landmarks, such as the isles and karsts of Ha Long Bay, it could become beautiful if it were to incorporate some greenery.
“What I’m trying to show is that it’s possible to introduce life wherever we are living.”
Vertical gardens a key to Central Park’s success
Frasers chairman Dr Stanley Quek said there had been a lot of opposition from the community to the Central Park development, but most were all now very happy.
The gardens have been a key reason the development is now so well regarded, and regardless of costs – which are said to have been very high due to a new facade system needing to be developed to house the soilless gardens – the payoff in marketing and helping to forge a “social license to operate” has been invaluable.
Central Park project director Mick Caddey said the gardens were “one of the most visible expressions of Central Park’s commitment to sustainable urban living”.
The gardens were also a large contributing factor to One Central Park being named the best tall building in the Australasian and Asian region by the Council on Tall Buildings and Urban Habitat.
- See our article One Central Park wins regional tall building award
Dr Quek said there were a lot of native plants in the design so the walls could cope with the Australian climate. These were “not as attractive” as exotics, he told the audience, so he had called on Blanc to incorporate more exotic species.
“Patrick disagreed in the beginning,” Dr Quek said, but they had given Sydney “changing imagery” as the seasons passed.
“We’ll see very soon the winter flowers coming out. It’s a changing mural all the time.”
Blanc noted that he thought native Australian plants were very beautiful, though it was important to have exotics for their “different shapes”.
Dr Quek said that there were many green walls around the world, but many were quite boring. What Blanc did, he said, through his choice of plants and flowers, was create murals that brought artistry to the development.
Initial scepticism
Initially, Dr Quek said, there was a lot of internal scepticism because a compromise had to be made with some of the apartments’ windows needing to become smaller to fit in the vertical garden panels.
Part of the solution was to incorporate vines. Having a solid green wall was not an option, Dr Quek said, because people in high-rise residential wanted views. They also wanted privacy, however, leading to the steel cables that are now becoming snaked with vines.
One thing Dr Quek noted was the importance of maintenance, and making sure what they have envisaged does not get destroyed.
“I worry about residents cutting the vines,” he said. “I worry about human error.”
However, speaking to a sales manager, The Fifth Estate discovered there was as yet no information campaign or resources in relation to this provided to residents.