Vertical Greenery – the vertical dimension
Vertical greenery represents a new dimension in greenery-related infrastructure, where plants are incorporated within vertical surfaces. Traditionally, vertical greenery commonly involved climbing plants with adventitious, self-clinging roots growing directly on coarse building surfaces, twining plants growing on trellis and pergolas, or plants growing within the crevices of stacked rocks. In recent years, numerous contemporary systems have been developed for the growing of plants on vertical surfaces.
Components of the Vertical Greenery system
There are 3 basic components, namely plants, system and media, and irrigation.
There have been many different systems development, each experimenting with different ways of containing the media for vertical planting. However beyond the efficiency, weight, and suitability of the system and media, the more important criteria for a successful vertical greenery system are the plant and irrigation factors.
Typology
Generally, the various vertical greenery systems fall into two broad categories – support systems and carrier systems. Support systems are designed to guide plants up on the vertical surface, while carrier systems are designed to contain the media for planting on the vertical surface. The selection of systems is guided by the type of plants. Support systems, also commonly termed as “green façades”, allow climbing plants and cascading groundcover to grow on specially designed support structures.
In contrast, carrier systems are able to host a greater diversity of plants, including groundcover, shrubs, ferns, grasses, sedges and even mosses. Such systems are commonly termed as “living walls”.
Types of plantings
The selection of plants is crucial to the success of vertical greenery. The criteria for plant selection should be based on the type of systems, the intended planting concept, environmental factors, budget and expected degree of maintenance. A wide diversity of plants can be grown vertically.
The selection of plants for a vertical greenery system that will be implemented on the exterior façade of a building can be similar to that for green roofs. The plants should typically be able to tolerate dry conditions and thrive in high daytime temperature, intense sunlight and low soil moisture. This is especially so for systems with shallow substrates of 100 mm or less. Due to the thin profile and gravity, the substrate media dries up rapidly and contributes to the high rate of evaporation. This is why drought tolerant plants are sometimes a better choice, even though the vertical greenery system is fully irrigated. However, it is not an absolute criterion. With sufficient and targeted irrigation, appropriate planting media and system design, it is still possible to grow a wide variety of plants.