As the world grows increasingly vertical, it was only a matter of time before the humble garden followed suit. No longer limited by the space around and in-between, these tall structures can create magnificent places for green space. Welcome to the vertical garden.
A garden's survival relies on water and nutrients, along with sunlight and carbon dioxide to conduct photosynthesis. Soil is nothing more than a support for the roots.
In Dubai, as we well know, all the planting is grown out of sand and as long as the plant gets its basic four requirements then they can grow on rocks, tree trunks, and almost any surface.
In Malaysia, out of the 8,000 known plant species, 2,500 of them grow without soil. We have been growing plants without soil and artificial lighting since the sixties in a system called hydroponics that feeds the plant the nutrients it needs. The same system has been developed further to achieve the vertical garden, and can be used in both outdoor and indoor applications. First, a plastic lining is used to cover the wall surface – this stops moisture and the roots getting into and eventually damaging the wall – then a metal framed lattice is covered with a thick rot proof felt made from Polyamide. It is this felt that the roots grow into. An irrigation system provides a nutrient solution to the top of the garden, which slowly soaks the entire area, watering and feeding the plants in the process.
For indoor applications metal halide lights provide the plants with the necessary wavelength they require. These halide lights are energy efficient.
Because there is no soil the vertical garden is a very light structure at approximately 20 to 30kg per square metre. The fact that it is so light means that it can be used in very large applications, like the entire external surface of buildings. As there is an air gap in-between the garden and the wall that is cladding it, it also acts as an environmentally sound thermal and acoustic insulation. Not only that, it also acts as an air purifier. In addition to leaves and their well known ability to cleanse the air, the roots and all the micro organisms related to them act as an air purifying surface. Thus polluting particles caught by the felt are slowly decomposed and mineralised before ending up as plant fertiliser.
Many different kinds of plants adapt well to a vertical garden. Epiphytes (Greek for plant), for example, grow on other plants and are used to thriving in limited soil.
An indoor vertical garden should use plants that are used to low levels of lighting, such as The Cast-Iron plant and the Chinese evergreen. These can be easily identified as they usually tend to have large dark green leaves that help the plant photosynthesis. For external vertical gardens plant selection is determined by the local climate and the orientation.
The vertical garden is a great opportunity to bring life back into the urban environment, where garden space has become limited and a way for the individual without garspace or gardening experience, to bring life into the home.