The ups and downs of vertical gardens

With a growing number of vertical gardens sprouting in the UAE, we explore the phenomenon.

A vertical garden by field-leading French botanist Patrick Blanc in a corridor at the Sofitel Dubai The Palm Resort and Spa. Courtesy Patrick Blanc
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Vertical gardens, or living walls, are springing up across the UAE, as innovative new technologies, coupled with increased horticultural understanding, have expanded the potential design permutations of this living art form. From the interiors of restaurants, such as Leopold's of London and Aprons & Hammers at The Beach in Dubai, to the public areas of countless hotels, spas and offices across the UAE, vertical gardens are adding a new dimension to the country's design landscape.

The early principles of ­“botanical bricks” (as they were dubbed in the 1930s by Illinois landscape architecture professor Stanley Hart White) have been built on, and now the creative possibilities for these green style statements in domestic and corporate design schemes are becoming evermore ambitious. Several hundred square metres can be covered at a single site, while a series of complex shapes, complete with built-in irrigation and drainage, can be created and maintained.

Not to be confused with a green facade, whereby plants grow from the ground up to cover a vertical surface, living walls gain their sustenance and are irrigated at their contact points across the entire vertical surface. They remain connected to, but separate from, the actual fabric of the building – essentially forming a living second skin.

Systems for the gardens can be soil-based, whereby planting is made in a variety of pockets, but the unique selling point of newer living walls is the adoption of soil-free systems and hydroponics. These enable designers to create lighter vertical gardens, and hence larger ones, because their weight doesn’t negatively impact on the structure of the building, and getting appropriate nutrition to the plants is simplified.

French botanist Patrick Blanc is considered a leader in this field, pushing the boundaries of vertical gardens and further popularising this form of planting. Excellent examples of his work can be seen at the Sofitel Dubai The Palm Resort and Spa, where a stroll alongside one of the hotel’s living walls is like a mini excursion to a rainforest.

Blanc has spent time in the actual rainforests of South East Asia and elsewhere, studying the indigenous plants he found there and observing how species are adapted for growth on tree trunks and branches, as well as soilless habitats such as granitic outcrops, limestone cliffs, caves and waterfalls. Plants found at these locations form the basis of planting plans for indoor vertical gardens around the world. However, exterior schemes, especially those in the UAE, have different climatic conditions to contend with, and the approach and species used must vary accordingly.

According to Blanc: “Soil is nothing more than a mechanical support. Only water and the many minerals dissolved in it are essential to plants, together with light and carbon dioxide to conduct photosynthesis … thus the core innovation [for vertical gardens] is to use the root ability of the plants to grow not only in a volume of soil, but also on a surface; this is just what they do in their natural environment when their roots are growing on tree barks or among mosses covering rocks.”

Vertical gardens are “a way to add nature to the daily life of city inhabitants”, Blanc adds. It is little secret that the ability to connect with nature in urban centres enhances psychological well-being, while cooling the environment and benefiting air quality. In built-up environments, where there is little room left for large-scale planting schemes in the traditional sense, planting vertically is the perfect solution, as seen increasingly in cities across Europe and the US, and now the UAE.

Ajayan Vasudevan, a project manager and horticulturalist at Acacia, a subsidiary of the ­Dubai-based landscaping contractor Proscape, has worked on a number of vertical garden projects across the UAE and wider region. To date, the company has installed in excess of 1,000 square metres of vertical gardens – the largest being a series of installations spanning 250 square metres at the Hyatt Regency Dubai Creek Heights. Currently in the pipeline is a project for a new terminal at the airport in Muscat, which will cover a total area of 450 square metres.

Acacia exclusively uses a patented “Biotecture” system for its living walls. This features a by-­product of basalt volcanic rock, spun to create a firm fibrous material that’s then moulded into a series of “stone wool” panels. Plants for the walls are cultivated in six-centimetre pots, which are then inserted into circular holes cut into the panels.

The material is insulated from the back to prevent leakage, and serviced by an ingenious system of irrigation and drainage pipes, which supports hydroponic growth for the living wall. Gravity ensures that irrigation reaches all plants, while drainage channels take away any excess water (it’s essential that a minimum gradient is achieved, or the water won’t flow through the system). In time, the soil plugs around the plant’s root system erode, and the plant’s roots expand into the fibrous material. It’s through this that food is delivered to the plants.

A small pump room needs to be situated near to the installations, from which NPK fertilisers (nitrogen, phosphorus, potassium and micronutrients) can be added to the water system to feed the plants. This is all they need to sustain them. Another key consideration for interior installations is lighting. Typically, plants need 12 to 14 hours of light a day for optimum growth; if this can’t be achieved naturally, additional lighting solutions are installed.

A benefit of the panel system is that the planting can be done off-site, and the plants can become semi-established. The vertical garden design can then be dismantled like a jigsaw, and reinstalled in situ, as a more complete piece, after four to six weeks.

Vasudevan sketches out his designs, which can range from the naturalistic, with drift planting that mimics what can be found occurring in nature, through to more prescriptive requests, which have included a representation of a UAE flag and a company logo at Silicon Oasis in Dubai. “They wanted their logo to stand out, so I had to make that with plants – it makes my life more challenging because it needs regular trimming during maintenance,” Vasudevan says. The installation for that particular project had to be done within two days, and the team worked day and night to get it finished.

As a rule of thumb, the plants used for interior projects are sourced predominantly from the Netherlands, but for exterior projects, Vasudevan prefers to utilise Acacia’s own nurseries locally. Experience has shown which species work well – and which don’t.

While popular with a number of domestic and smaller installations, succulents aren’t generally used by Vasudevan because their rates of growth and water requirements are contradictory to other plants – plus they are heavy. Either a scheme has to be populated entirely by succulents, or by other plants with similar growing requirements, or it will not ­synchronise.

“Indoor walls consume about one litre of water per square ­metre, per day, compared to outdoor walls, which consume five to six litres per square metre, per day – both of which contrast favourably to consumption rates of external landscapes, which typically consume 20 litres of water per square metre, per day, for grassed lawns or other horizontal ground cover,” Vasudevan explains. “The first question that a new client asks is the price, and I’m always reluctant to give this unless I have the full drawings and planting plan, but as a very general guide, an approximate budget of Dh4,000 per square metre would include design, supply and install.”

This is a considerable investment, particularly in larger commercial applications where a wall may cover 50 to 100 square metres. Vasudevan advocates an additional investment of 10 to 15 per cent of the installation cost for annual maintenance. It’s a living wall, after all, and plants will continue to grow and need care indefinitely. At the Hyatt Regency Dubai Creek Heights, for example, Acacia’s specialist team visits between the hours of 11pm and 6am, three or four times a week, working through the night to ensure that the display remains perfect.

Once a project is delivered, ­Acacia clients are given a large ring-binder file packed with pages giving clear and comprehensive care directions for their living wall. Vasudevan laments that when maintenance is outsourced to other organisations, the walls don’t always thrive.

Unsurprisingly, Vasudevan sees such investment in vertical gardens as paying dividends for his clients. “I look at the Hyatt ­Regency, which incorporates a lot of unusual shapes in its living wall, and I see a lot of people taking selfies with it, or TV programmes being made there with the wall in the background. With proper maintenance, the condition looks fantastic. The plants help to purify the air and add beauty to the interiors.”

Expert tips

Sweden’s Vertical Garden Design has created living walls in projects around the world – from Stockholm’s Hotel Kungsträdgården and Espaco Espelho d’Agua in Lisbon to The Zone in Rosebank, Johannesburg, and the Replay store in Barcelona.

Michael Hellgren, landscape architect at Vertical Garden Design, is passionate about the effects of a living wall.

“When I first saw vertical gardens, I was fascinated by this wild impression that plants could give in such an environment,” he says.

“Often plants in ‘normal’ gardens are organised and controlled in a way that this liveliness is lost. With vertical gardens it felt possible to, within a very limited space, have a piece of thriving nature right in the most urban of contexts – that is an interesting contrast to work with.”

Michel Hellgren offers his top three tips for those looking to instal their own vertical gardens:

• As for any garden, using the right plant in the right place is a key consideration for vertical gardens. That means matching the growing conditions offered with plants that in nature grow in similar conditions. So it’s an advantage to evaluate temperature, sun, light exposure, humidity, water quality etc.

• Maintenance of a vertical garden is not difficult. As with a normal garden, it needs regular check-ups and pruning a couple of times per year. The most critical thing is water supply.

• There are DIY kits that can be useful, as well as online videos explaining how to make vertical gardens with materials from your local hardware store. Choosing the right plants is important, so it pays to do a little reading on prospective plant candidates.