The engineering behind vertical gardens – how the plants are chosen, installed and kept alive
- Vertical gardens and other green features are becoming more common in cities around the world, but how are they maintained?
- We talk to designers about the evolving science behind green features, experiments that failed and others that worked, and how such gardens are maintained
Visions of skyscrapers swathed in living greenery dominate present-day urban planning. Like the erstwhile parsley on a plate of food, such fanciful plantings are not mere window dressing, but an accepted component of sustainable cities.
Pushing the envelope in Hong Kong is New World Development. Its premium office development K11 Atelier King’s Road, in Quarry Bay, opened in 2019 with a total of 6,700 square metres (72,000 square feet) of greenery – some 217,000 plants – equivalent to 220 per cent of the site area. (The upside-down olive trees out the front are artificial, included to represent an image of the future and a linkage between humans and the earth).
This expansive green coverage was achieved via four elements of planting: at street level, on the vertical facade and rooftop of the 22-storey building, but also incorporating an experimental green roof on the underside of the arrival plaza – an idea Edwin Chan, senior project director of New World Development, believes has never been tried before.
The aim was to soften the harsh aesthetic of a former industrial neighbourhood and help mitigate the heat island effect that keeps densely built city areas warmer than surrounding areas. But not every element of the planting worked as expected.
The arrival plaza’s patented Ceilingreen is in effect an inverted green roof, designed to provide a landscaped area the size of four tennis courts without sacrificing the common space for the streetscape and neighbourhood.
A system of vertical planting developed in-house by the New World team – where the plants are rooted in fibreglass trays using a sponge and soil system and hung upside down with automated watering and artificial light – was successfully trialed off-site over three years, using a variety of plant species.