Vertical Garden: An Introduction

A vertical garden is a wall, either free-standing or part of a building, that is partially or completely covered with vegetation and, in some cases, soil or an inorganic growing medium. The vegetation for a green façade is always attached on outside walls; with living walls this is also usually the case, although some living walls can also be vertical garden for interior use. They are also referred to as living walls, biowalls, vertical gardens or more scientifically VCW. (Vertical Vegetated Complex Walls)

Vertical Garden Categories

There are two main categories of vertical garden: green façades and living walls. Green façades are made up of climbing plants either growing directly on a wall or, more recently, specially designed supporting structures. The plant shoot system grows up the side of the building while being rooted in the ground. With a living wall the modular panels are often made of stainless steel containers, geotextiles, irrigation systems, a growing medium and vegetation.

There are three types of Growth Media used in living walls, loose media, mat media and structural media.

Loose medium walls tend to be "soil-on-a-shelf" or "soil-in-a-bag" type systems. Loose medium systems have their soil packed into a shelf or bag and then are installed onto the wall. Loose soil systems are not well suited for areas with any seismic activity. Mat type systems tend to be either coir fibre or felt mats. The method of reparation of these systems is to replace large sections of the system at a time which compromises the root structures of the neighboring plants on the wall. This inefficiency requires that these systems have a water re-circulation system put into place at an additional cost. There is some discussion also around "active" living walls.

An active living wall actively pulls or forces air through the plants leaves, roots and growth medium of the wall and then into the buildings HVAC system to be recirculated throughout the building. This means that active living walls do not improve air quality to the point that the installation of other air quality filtration systems can be removed to provide a cost-savings. With further research and UL standards to support the air quality data from the living wall, building code may one day allow for our buildings to have their air filtered by plants.

Function of Vertical Garden

Vertical garden are found most often in urban environments where the plants reduce overall temperatures of the building. Living walls may also be a means for water reuse. The plants may purify slightly polluted water (such as greywater) by absorbing the dissolved nutrients. Bacteria mineralize the organic components to make them available to the plants.

Living walls are particularly suitable for cities, as they allow good use of available vertical surface areas. They are also suitable in arid areas, as the circulating water on a vertical wall is less likely to evaporate than in horizontal gardens.