Vertical gardening – living walls

The Living Wall; Vincent van Gogh, A Wheatfield, with Cypresses, 1889

In 1889, when Vincent Van Gogh was a patient at the St Rémy mental asylum near Arles, he painted one of his most beautiful paintings, A Wheatfield, with Cypresses. The masterpiece makes you feel as if you’re weaving your way through fields of golden wheat on a warm day, the stalks rustling against your legs. Van Gogh’s strong, distinctive brush strokes of bold colours evoke softly and simply the shapes of the sky and landscape. Light floods our senses; we can just imagine inhaling the air – feeling enriched and enlivened.

Until the end of October (in 2011) one can see two images of the painting outside London’s National Gallery, one is a photograph and the other is growing on a wall. Eight thousand plants – 26 varieties – were used to replicate the tones and forms of the painting, making it literally come to life. Sponsored by General Electric, the endeavour helped to publicize the Gallery’s commitment to saving energy. The painting and the initiative are both environmentally sensitive and friendly – could the Gallery have chosen a more fitting work of art?

Indeed, the living wall is an impressive example of the growing worldwide phenomenon of vertical gardening.  You’ll discover a living wall growing on the Athenaeum Hotel in Piccadilly, London, the Caixa Forum Museum in Madrid, the Musée du quai Branly near the Eiffel Tower, and the Grant Thorold Library in Grimsby, England. Others adorn shops and shopping centres. Inside the Taipei Concert Hall there’s one entitled ‘Green Symphony’; and perhaps one of the most enchanting feats of gardening in the sky is Jeff Koons’s 43 foot tall Puppy, created with a steel substructure and bedding plants to look like a Highland Terrier. It stands guard at the Guggenheim Museum, Bilbao.

Patrick Blanc, a French botanist, is the person credited with the birth of the contemporary living wall in the late 1980s. Studying the vegetation and flora of tropical climates made him realise that ‘plants could sprout at any height, not merely from the ground, in order to then climb. That is the difference between soil based creepers and the epiphytes or lithophytes [plants deriving moisture and nourishment from air and rain] that colonize any favourable spot on a branch or rock.’ Blanc reckoned that ‘herbaceous and shrubby plants could colonize any available support, whether dry or soaked, in direct light or in the deepest shadows of the understory … along roadsides, on a lone boulder, or on the stones of temple ruins.’

Indeed, Blanc’s aesthetic sensitivity has inspired many to credit him as an artist. His work adds fresh elements to architecture and cultural enterprise. Like horizontal gardening, the shapes, tones and depths of living walls, and vertical gardening in general, given the appropriate light, temperature and irrigation, may appear at times like moving images,  one could suggest they are like documentary ‘films’ about the natural world. By bringing nature into urban evolution in the form of green paintings and sculptures, Blanc has cultivated a fresh artistic genre.

Blanc’s vertical gardens do not rely on soil (though they may be seeded in soil). Plants may grow on a solid, waterproof, non-toxic and rot-proof surface – like felt and comparable to a thin layer of algae or moss – which is fixed with staples or glue to a wall frame. The roots develop around the fibres of the cloth and do not have to spread far in order to find water. Growing plants without soil is called hydroponics. Aeroponics is another system for growing plants on a vertical surface. This entails spraying plants with a mist containing nourishment.

Alternatively, many garden walls, such as the one at the National Gallery, rely for nutrition on pockets of soil as well as water or mist and fertilizer. Walls are constructed with standardized flat units incorporating pockets or cells that hold the soil and individual plants. Relatively speaking, this modular, soil-based mode makes for relatively easier assembly, installation and maintenance, though it’s physically heavier. It can enable a small-scale DIY option for homes.

For most walls, a timed, automatic irrigation/humidification system spreads moisture infused with nutrients.  A trough or a similar object collects run-off water; a pump sends it back up the wall. Watering is adjusted according to the prevailing climate. Light can be adjusted for interior and exterior walls. The geographical location of the wall and whether it’s inside or out will have a great bearing on the plant choice and placement – a tapestry come to life.

Living walls have positive benefits. They reduce the wind chill factor, absorb noise and carbon dioxide, and provide clean oxygen and a natural habitat for wildlife, such as bats, birds and butterflies. Inside the building, they help to reduce heat loss, hence cutting energy demand; and where buildings are sealed to maintain air temperature, they help to purify the air.

But at present it’s still questionable as to how environmentally sustainable living walls are. The power used to irrigate and create the structural apparatus creates carbon dioxide. Routine maintenance is essential. They can entail an excessive use of fresh water in comparison with most horizontal gardens and, unless they are very small in scale, watering with a hose is not a viable alternative to an irrigation system. Hence, most of these spectacular and enterprising developments are to be found in corporate settings where the resources for design, installation and maintenance are available.

Dan Curran, a professional landscape gardener with over 30 years’ experience in the field, is passionate about the natural beauty of walls brought to life with a mixture of evergreen and seasonal climbers, such as Ceanothus, jasmine, ivy, wisteria and Virginia creeper. He considers the  living walls  ‘far too labour intensive, complicated, blatantly artificial, faddish; the people that do it say they’re the best thing since sliced bread, but the quality of the bread’s inferior to the old fashioned loaf.’ For art’s sake they’re impressive, concedes Dan, but we shouldn’t be led up the garden path on account of their mythical sustainability.

Angus Cunningham, Director of Scotscape, which helped to install and now maintains the National Gallery’s living wall, takes a more conciliatory view. Further research and development could ensure they are sustainable, believes Cunningham. Even at present some walls are more sustainable than others, depending on the method of nourishment and irrigation system employed. Roughly speaking, though the walls cost about £500 per square metre to install, the usual minimum initial outlay is £5000 and maintenance costs can reach some £150 per month. They require pruning and sometimes re-planting; irrigation systems can be remotely controlled but site visits are still vital; and what if, I wonder, the irrigation system breaks down or clogs up? Regardless, the business of living walls is blooming (!).

One relatively sustainable vertical garden could be the ‘skyscraper farm’ – where urban agricultural products are cultivated in multistorey groupings or tower-like structures, or on top of terraces and roofs. These ‘farms’ could provide a non-seasonal supply of products and would be less vulnerable to droughts and floods. They’d reduce the need for transport and the burden to find more land to feed an increasing population. They would provide new job opportunities in the city. (Over half of the world’s population live in cities.) Their presence would make people more aware of the connection between what we eat and where it grows – and possibly more supportive of environmentally sustainable initiatives.

According to one acclaimed authority, Professor Dickson Despommier of Columbia University, a 20-storey vertical farm could potentially feed 50,000 people. To feed New York, about 180 would be required. Aesthetically, they could be quite pleasing and vertical space is plentiful.  Imagine almost fully glazed skyscrapers revealing light-reflecting hues of green, at night the lights evoking an almost surreal air; this is the stuff of science fiction.

Whether we’re looking at pictures nurtured on walls or transparent skyscrapers of nourishment, looking up at greenery on the horizon inspires joy and excitement, adding colour and life, touches of whimsy, to the sometimes stifling grim and grey of urbanity. Whenever I’ve passed by the great green wall at the National Gallery, there have been people from all over the world admiring it, taking pictures of the image and themselves standing and grinning in front. ‘It softens everything,’ a woman from Scotland remarked, almost transfixed. ‘They should do more of it. I love the different colours and shades.’ A Russian woman said, ‘it’s beautiful.’ An architecture student from California told me that living walls are now a studied building technique in his course. He’s convinced that they make you more aware of the environment; they make you think about the world.

Maybe this is what makes vertical gardening worthy of the space, indeed sustainable in an indirect way. Its beauty and utility incline us to preserve what we feel we’re in danger of losing – our living space above, below and beyond – while enriching our cultural heritage in a novel way. A most worthy postmodernist movement? If Van Gogh were alive today, what would he think?

Photograph ©The National Gallery

This article first appeared in Cassone: The International Online Magazine of Art and Art Books in the October 2011 issue.