Super Tree Grove, Gardens by the Bay - Singapore

Vertical Gardens - the Ultimate in Organic Architecture

by | 15 Aug 2018 | Organic Architecture

A vertical garden as the name suggests consists of multiple plants grown vertically, generally on a wall or other supporting structure. Found in nature and ancient civilizations, probably the most famous were the Hanging Gardens of Babylon, one of the seven wonders of ancient architectural history.

Today, vertical gardens come in a wide variety of forms, from simple proprietary planting pockets or pots, to highly sophisticated purpose-built planting structures. They can also be applied both internally and externally.

Benefits

Whilst vertical gardens are often created purely for their aesthetic appeal, they also offer many other tangible benefits.

Biophilia

Biophilia is defined as a love of life and the living world and describes humanity’s innate tendency to seek connections with nature and other forms of life.

Vertical gardens are biophilic designs that integrate natural elements, materials and forms into architecture. Often incorporating a wide range of plants, research has demonstrated that a mix of species can have a potent biophilic effect, providing measurable physical and physiological benefits including:

  • reduced stress levels
  • enhanced cognitive function and creativity
  • a deeper sense of happiness and well-being
  • an ability to heal faster.

Air Quality

For those of us living in urban environments, 90% of our lives are spent indoors learning, working, socialising, relaxing and sleeping. Living in air-conditioned environments that contain toxins such as formaldehyde, VOCs, trichloroethylene, carbon monoxide, benzene, toluene and xylene, this is a strong mix that can have a serious impact on our health.

Vertical gardens reduce the carbon footprint of a building by filtering these pollutants and carbon dioxide out of the air. A recent NASA study concluded:

  • plant leaves and root micro-organisms can remove toxins from the air within buildings
  • certain tropical species are more efficient than others
  • increased oxygen released from plants helps keep people awake and alert.
Super Tree Grove, Gardens by the Bay - Singapore

Super Tree Grove, Gardens by the Bay – Singapore

Thermal Benefits

External Walls

The Urban Heat Island (UHI) effect is a result of the land and atmosphere being modified when we build cities creating metropolitan areas that are a lot warmer than the rural areas surrounding them. Combined with the energy created by people, cars, buses, and trains buildings and hard surfaces absorb the sun’s heat which is then emitted back into the surroundings.

External vertical gardens can contribute to reducing this effect and make our future cities more sustainable by:

  • reducing absorption of thermal energy transmitted through building walls to inner surfaces.
  • decreasing the need for air-conditioned cooling systems.
Lanikai Apartments, Southport

Lanikai Apartments, Southport

Internal Walls

Internal vertical gardens featuring a range of lush, green plant species can also contribute positively to improving the environment by:

  • reducing air temperature
  • balancing humidity levels
  • increasing airflow.

Acoustics

Hard surfaces commonly found within buildings can result in reverberation creating distracting noise.

Internal vertical gardens have been demonstrated to:

  • increase wall sound absorption co-efficiency
  • enhance speech privacy
  • improve ambient noise levels of office environments

Food Production

Traditionally trellises and other simple supporting structures have been used to promote vertical growth of plants including edible varieties, however today, commercial food production is far more sophisticated.

Agribusiness, the commercial production of leafy greens, herbs or plant seedlings using multi-level growing systems is rapidly expanding around the world.

These are typically grown as vertical gardens in a fully enclosed and climate-controlled environment, offering a simple way to boost growing space.

Since they don’t rely on fertile arable land and can be established in any climatic region globally, irrespective of seasonal daylight hours or extremes in temperature, they offer much greater flexibility than traditional farm practices.

This avoids seasonal cropping limitations increasing production, and removes external pressures such as disease, pest or predator attacks which cause crop losses in traditional farming.

Produce quality is also consistent and reliable.

Indoor vertical garden farming

Indoor vertical garden farming

Design Considerations

Since most plants rely on growing in soil which is rarely found on vertical surfaces, creating a successful vertical garden needs careful pre-planning and skilled design. Anyone familiar with nurturing pot plants will be aware of the potential problems that can be encountered maintaining healthy plants in a confined pot environment.

Host Wall

As the foundation for the vertical garden, the host wall needs to perform a number of important functions including;

  • Be capable of supporting the load of the entire system including the plant containers and support structure, the growing medium (soil), the plants themselves, irrigation and lighting.
  • This load needs to be based on a saturated garden, as water considerably increases the weight of the installation.
  • Waterproofing to protect the host wall from the majority of irrigation water flow and avoid the risk of any long term water damage.
  • Orientated and located to provide the most favourable growing conditions.
An unconventional host wall - Ta Prohm Temple, Siem Reap

An unconventional host wall – Ta Prohm Temple, Siem Reap

Plant Selection

Many plant species are not suited to growing in a confined root environment necessary for a successful vertical garden. Even plants that can be readily propagated in pots, can behave differently when grouped together in close proximity to other plants.

Consideration needs to be given to mixing plants that enjoy the same growing environment, and that have a similar growth rate to avoid a more aggressive plant outgrowing and overshadowing its neighbours.

Gravity also needs to be considered as water will drain down through the garden from the top to the bottom, resulting in drier conditions at the upper tiers, and potential for waterlogged plants at the base.

Plant selection is also based on consideration of many other factors including:

  • location of the wall
  • orientation of the wall faces
  • amount of sunlight and/or natural light
  • amount of shade
  • climate
  • type of vertical garden (internal or external)

Certain plants better suit different environments. Horticulturalists specialising in vertical gardens can be consulted to recommend suitable aesthetic and practical plant palettes for the particular application.

The Island Courtyard – Surfers Paradise

The Island Courtyard – Surfers Paradise

Growing Medium

Selecting the appropriate growing medium to ensure the plants have the best chance of growing healthily and receive the nutrients that they require will depend on the plants selected, and the garden system adopted. Soils and hydroponic mixes offer different characteristics that need to be matched with the plant selection;

  • Porosity and drainage.  It is generally desirable for the growth medium to hold some moisture, however if it becomes waterlogged, it can impact on the plants health promoting funguses and root rot.
  • Weight. Dry and wet weights can vary significantly and may impact on the strength of the support structure or host wall.
  • Nutrients. Plants can receive their required nutrients through fertilised soil, or hydroponically through the water they are fed.

Watering System

Whilst it is possible to manually water vertical gardens, a more reliable option is to irrigate them with an automatic system that supplies each plant directly with the water and nutrients it needs. This ensures:

  • Long term plant health.
  • Water flow is kept within the confines of the vertical garden.
  • Lowest water consumption rates.

The Irrigation system needs to account for the geographic location, humidity, temperature, sunlight, shade, wind and the following factors:

  • Amount of water each plant requires.
  • Frequency of watering
  • Fertilisation requirements.
  • Minimal excess water drains through the garden requiring collection or drainage.
Cloud Dome, Gardens by the Bay, Singapore

Cloud Dome, Gardens by the Bay, Singapore

Lighting

The location and orientation of external vertical gardens should take into account the amount of natural light they will be exposed to during different seasons and times of day.

Walls that receive little direct sunshine generally thrive as vertical gardens, whilst western facing walls exposed to afternoon sun are the most challenging, requiring hardy plants.

Indoor plants are extremely sensitive to light and require a carefully designed and constructed environment to survive.  If a vertical garden doesn’t receive adequate natural sunlight or ambient light, artificial lighting will be required to support photosynthesis which is vital to plant life.

This is typically provided by the installation of Metal Halide Lamps which emit UV light, however as this is a stark unattractive light source, it is recommended that the lighting system operates outside of business hours.

Plants are subject to a circadian rhythm and need periods of darkness balanced with light to survive, so it is important to ensure the correct timing of artificial lighting takes this into account.

Creative use of effect lighting can also enhance the dramatic visual aesthetics of a vertical garden.

Maintenance

Vertical gardens generally need ongoing maintenance. Comparable to caring for a cellar of fine wine, if done well the wines will improve with time. If not then just like wine, plants can quickly turn and spoil.

Ongoing maintenance typically involves;

  • removal of shedding foliage
  • trimming of plants
  • testing the irrigation system
  • testing grow lights
  • refilling fertiliser
  • pest management
  • seasonal refurbishments of plants

Vertical gardens if well designed, installed and maintained won’t just look good, but will also provide numerous positive benefits to your living environment.

A simple cloth pocket vertical garden

A simple cloth pocket vertical garden.

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