What’s the difference between planting vertically and horizontally?
Vertical gardens rely on an innovative way of growing plants without any soil. Instead, these plants are grown on felt sheets, because soil is actually nothing more than a mechanic support. Only water and the many minerals dissolved in it are essential to plants, together with light and carbon dioxide to conduct photosynthesis. Some vertical garden design is based on engineered panels of all sorts of plants, but I only use plants that grow wild on rock faces. Throughout history, plants have found a home on walls, but these seedings don’t always work in harmony with the architecture, and they can even break down the structural integrity of a building’s facade. Whenever roots are allowed to grow deep inside a wall, they can easily damage the wall and cause its destruction. That is precisely what happened to the Angkor temples in Cambodia. This root-related damage can be prevented if water is regularly given to plants. Roots then only spread on the surface, leaving the inner wall unaffected.

What benefits can vertical gardens bring to an intensely urban environment like Kuala Lumpur?
There are many natural benefits, especially for a city like KL that is short of green space. The vertical garden allows man to recreate a living system very similar to natural environments. It’s a way to add nature to places where man has removed it. Any naked wall in Kuala Lumpur has the potential to be turned into a vertical garden and thus be a valuable shelter for biodiversity.

For a city with high levels of pollution, the vertical garden also acts as an efficient tool for air and water remediation wherever flat surfaces are already extensively used for human activities. The idea is that polluting articles are taken in from the air and are slowly decomposed and mineralised through the felt before ending up as plant fertiliser.

So effective vertical gardens in KL could improve the air quality, bring down energy consumption and act as a natural shield between the city’s weather and its citizens. In fact, there’s huge potential for KL, because Malaysia itself has such a lot going for it. Out of the country’s 8,000 known species, around 2,500 grow without any soil.

Can you give us an insight into what you’ll be doing at Kenny Heights?
To begin with, my role is to cover some places with plants on Kengo Kuma’s project, and I’ll also be looking at the outside walls on other buildings. It might be that I can do something with the wall along the road to the Kenny Heights entrance, which is big, ugly and concrete.

But for the moment, I’m focusing on Kengo Kuma’s buildings. I’m designing for the outside walls – which is typical for me. These are concrete and not too big. However, on one side of the building, the windows open onto the exterior wall of another building, which is only a metre away. So I’ll treat that one as an interior wall.

How does your approach to exterior and interior walls differ?
Well, outside offers more light, so I shall use a large number of species that grow on the region’s limestone cliffs for the exterior walls. These are light-demanding plants, which tend to be big and fluffy, and have more flowers. And in the canyon-like space between the two buildings, I’ll use shade-loving species. I’m thinking of plants with delicate foliage, along with mosses and ferns, to create a soft effect. Of course, there are many shade-loving, under-canopy species that are found in Asia’s tropical rainforests, and they will thrive in this shaded environment. And because this area will be totally protected from natural daylight, it will need some artificial light. I hope the ultimate effect will be similar to being in front of a cliff covered with foliage.

How will your design complement Kengo Kuma’s architecture?
I’m quite used to working with international architects. I’ve done planting schemes on buildings for people like Jean Nouvel, Andrée Putman, Herzog & de Meuron and Marc Newson, and quite often we have precise discussions about what is to be done.

I met Kengo Kuma in Tokyo to discuss this scheme. It’s going to be good, because he works with wood, and that contrasts well with soft-leafed plants. It will be an interesting mix and contrast.

What have you discovered about planting in Malaysia?
When I was last in Kuala Lumpur for discussions on Kenny Heights, I visited Sungai Buloh, a great place for finding the best nurseries. I was really impressed by the high level of plant diversity in these nurseries. I’m very confident about this project as the area provides all the species I need for both the outdoor vegetal walls as well as the more or less canyon-like vegetal walls.

How creative will you need to be to get the best effect for Kenny Heights?
I’m a botanist by training, though some people think I’m a bit of an artist. But nature is the only artist.

The work of Patrick Blanc promises to redefine the urban experience of vegetation. Since the late 1980s, Blanc has focused on the creation of the vertical garden, a dense collection of sub-tropical plants installed into a custom-built architectural framework with built-in provision for moisture and nutrients. Blanc’s walls have become an integral element in many key modern buildings, including Jean Nouvel’s Musée du Quai Branly in Paris, and Herzog & de Meuron’s CaixaForum in Madrid. His installations can also be found in Melbourne, New York and Japan. In each case, Blanc’s ambitious botanical sculptures blur the boundary between artwork, architecture and garden, featuring accumulations of lush tropical vegetation that are so densely packed and carefully selected that they last for many years without maintenance.