Burgeoning from the walls of museums, hotels and the Qantas first-class lounge, this diverse, bouffant greenery gave no sign of its underpinnings and no hint of its dietary needs. Even when Blanc’s secret support system was revealed, the apparent weight of the exotic botanicals seemed to belie the simple slots in Blanc’s geotextile fabric wrap – clearly a very sophisticated mainten-ance and irrigation system was at work somewhere in the thick of it.

Traditionally, a green wall has constituted ivy and other climbers and creepers growing over a trellis, or anchoring into the wall itself. The benefits of covering external walls with deciduous plants that allow sun to hit a wall in winter, but shade it in summer, have been exploited by architects and building owners for centuries.

These green façades are created from the ground up, often with metal or plastic screen systems that use a variety of pins and brackets to space the screen off the structural wall, and prevent insidious tendrils penetrating the building. There may be integrated irrigation devices and rainwater storage to ensure that the vines remain consistently green, but fundamentally it is classic horizontal agriculture at work.

Living green walls of the Blanc ilk are something different: an attempt to recreate the situations in nature where plants cling to rock walls in moist environments, their roots fed by a nutrient-rich runoff solution. It’s a much harder scenario to get right.

Around 2009, as public interest in the concept of planting walls was growing, the first ‘copyist’ Blanc-like green walls started to die. The UK’s first vegetated wall, on a children’s centre in Islington, North London, was 
a particularly public failure, but subsequent projects like an epic 221-square-metre seasonal planted sign on the PNC Bank in Pittsburg, more ground-breaking work by Blanc and ‘green graffiti’ projects like artist Anna Garforth’s ‘Grow’ writing in moss, perpetuated the genre of wall-bound plants.

Meanwhile, the concept of urban farming was taking root among designers and city dwellers, who had 
only vertical indoor and outdoor spaces to grow upon. Enter the humble flowerpot to democratise living walls by inspiring a slew of vertical grow-it-yourself green wall systems.

Modular living green walls – as opposed to the freeform custom creations of Blanc, et al. – fall into two types: those that are essentially a vertical hydroponic system, planted in an inert medium and fed with nutrients; and those that exist as a series of window box-structures planted with lightweight potting mix. At the low-tech end are personal, vertically-mounted containers like the playful Woolly Pockets, designed by brothers Miguel and Rodney Nelson, featuring ‘internal moisture control’ and made from recycled bottles. Essentially a soft wall planter, Pocket plants are watered by hand or mounted on a tiny watering tank.

The Kickstarter-funded ‘Urbio’ modular panel-and-container system is another successful domestic-scale green wall system, combining the organic forms of felt with the practicalities of ‘eco-plastic’, and fixing the plant containers in place with strong neodymium magnets. Seeking US$15 000 to realise their concept, ‘lifestyle product designers’ Jared Aller and Beau Oyler crowd-sourced almost US$75 000 in mid 2011, enabling them to tool up, and then some. Award-winning South African designer Haldane Martin was not so lucky: despite a fetching green wall concept nesting rotomoulded pods into a hexagonal steel wall frame “biomimicking the space efficient packing of bees”, he is still seeking funding.

Bridging simple wall-mounted containers and domestic-scale modular irrigated green wall systems is the 
Windowfarm. Founded as an open source design by New Yorker Britta Riley, the original DIY Windowfarm arrangement of hanging PET bottles, clear plastic tubes and a low-powered pump, is now supplemented by 
a crowd-funded variant sold in ‘columns’, for hydroponic vegetable cultivation.

Riley’s design started out as “a bunch of leaky buckets and plastic things … cobbled together” in order to create something useful and replicable from everyday objects. The design is now in its fourth iteration and the Windowfarm open source online community has more than 33 000 participants eagerly tending micro-crops of herbs and vegetables.

For something more permanent and outdoor, there is Australia’s own Junglefy. Currently working with Jean Nouvel and Patrick Blanc on ‘Central Park’ in Sydney, constructing what will be the world’s largest 35 000-plant-strong green wall, the Junglefy team has developed a proprietary system of recycled plastic containers fixed to a sub-frame with integrated irrigation. Importantly, their pump is powered by solar.

In order to lighten the load on wall-fixed support structures, most living wall containers hold lightweight planting mediums like coconut fibre, and then rely on water-fed nutrient-rich irrigation to sustain the plants. Heavy rain and strong winds can scour pouches and containers of their lightweight mix, and nutrient delivery systems are notoriously difficult to get right.

Horticulturalist and biologist David MacKenzie, owner of the widely used LiveRoof green roof system, spent almost five years researching existing planted wall systems before coming up with his own. His focus on the water delivery systems identified the pump-up and trickle-down feed system as fundamentally flawed, because plants at the top become waterlogged and fungal, and those diseases are then transferred downward in the water stream. MacKenzie surmised that in order to flourish plants need “vertical orientation and water from above, like rain”.

In June 2012, MacKenzie launched his LiveWall design, featuring a mounting system housing spray, rather than drip, irrigation, supporting modular containers planted with lightweight potting mix. On display at Greenbuild in November 2012, the system looks simple, robust and effective, although somewhat blocky while the plants are still growing in. Importantly for the space-compromised urban farmer, the containers are roomy enough to grow vegetables and herbs.

The LiveWall could take a leaf from Junglefy’s book though: architects for the new US Department of Homeland Security building decided not to proceed with a proposed green wall when they discovered the energy cost of irrigating it.

Possibly the ultimate sustainable green wall solution, that shades and rustles, needs no water and makes its own power, owing more to the plastic palm than the flowerpot, is Solar Ivy. Developed by Sustainably Minded Interactive Technologies (SMIT), Solar Ivy is a new form of building cover comprising leaf-shaped tags of photovoltaic material hanging off a stainless steel mesh. It’s life, Jim, but not as we know it.

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