By Sandra Batley
Vertical gardens are providing us with a new and sustainable way of greening up our outdoor rooms.
Imagine a lush tapestry of plants growing vertically up the side of tall city buildings and urban garden walls, or plants thriving on the interior walls of offices, restaurants and cafes. Well, you no longer need to imagine these vertical gardens as green wall technology is now making them a reality.
The term “green walls” refers to vegetation that grows directly onto a building’s facade or on a freestanding wall. Also commonly known as living walls or vertical gardens, green walls make it possible to create and display a natural-looking landscape vertically that is completely manmade.
Perfect for greening up outdoor rooms, green walls are fast gaining popularity for the environmental and aesthetic benefits they provide. In an outdoor living space, green walls offer the perfect solution for adding a bit of “nature” to the area. Green walls are particularly ideal for small outdoor rooms where space is limited, such as on a balcony or in a small courtyard. There’s also the opportunity to grow vegetable and herbs on a green wall, effectively creating a vertical edible garden.
The good thing about green walls is they can be constructed inside and outside, leaving you with no excuse for not having a green home and garden. There are three main green wall systems that can have both external and internal applications:
• The hydroponic panel system usually compromises pre-planted panels that are brought on-site. The Hydroponic Panel System is connected to a customised rail-and-bracket system and then attached to the wall. It has a mechanical irrigation and fertiliser system, usually with a gutter drain at the bottom. It has been developed as a modular basket system used like cladding to create a ready-made green space.
• The soil-based panel system is another modular system that uses 500mm x 500mm panels made from rigid 80 per cent postindustrial polyethylene (the most environmental plastic) and is fully recyclable. It is simply attached to the wall by a recycled plastic mounting strip that spreads the weight across the panel, with two screws to secure it in place. Irrigation driplines are usually installed to control watering requirements.
• The felt system is a hydroponic technique where plants are fitted as seeds, cuttings or already grown plants into a layer of felt made of polyamide. The felt is rot-proof and its high capillarity allows good water distribution. This is then mounted on a 1cm thick PVC layer as a waterproof membrane, which is riveted to a lightweight metal framework. The felt is kept continually moist with water supplemented with nutrients. Watering and fertilising are also automated.
Green walls can be built out of any of these systems and in addition to being set up in an outdoor room, they can also be used to green up the inside of homes. Artificial lighting is required for green walls set up inside.
When considering a green wall, the orientation and climatic conditions of the outdoor room will determine the choice of plant species, as will the overall visual effect you want to achieve.
Once established, a regular maintenance program for your green wall is recommended. The best way to maintain a green wall is to have dripline irrigation with periodic fertilisation incorporated. Plant maintenance is as it would be in any garden setting: checking for weeds, dieback, overgrowing etc. The issue of maintenance can be addressed in the initial stages of planning the planting of the panels.
Long-lasting and stunning features can be created using green walls. Not only do these vertical gardens help to enhance outdoor rooms, they also help to create a more pleasant environment indoors. Green walls offer a new way to beautify the built urban environment, while adding a new dimension to our outdoor living areas.
• Increase thermal insulation (lowering energy costs)
• Lower greenhouse gas emissions
• Reduce noise pollution
• Polish grey and/or black water
• Can run on recycled or harvested water
• Clean the air, especially in removing VOCs (volatile organic compounds)
• Contribute to the good health of buildings and people
• Improve indoor air quality
• Provide a shelter for biodiversity
• Greatly reduce the harsh nature of many built urban structures