In the quest for sustainable living, urban landscapes are evolving, with nature being brought back into cities in innovative ways. Popular among landscape architects and designers is the installation of living green walls, also known as vertical gardens. These are not just a stylish way to adorn a building’s exterior; they offer numerous environmental, social, and aesthetic benefits. However, like any other concept, they come with their set of challenges. Let’s dive into modular living green walls, exploring their advantages, disadvantages, and how modular systems work.
What Are Living Green Walls?
A living green wall is any vertical structure covered or partially covered with vegetation. In nature, plants can be seen inhabiting holes and cracks in cliff faces and rocky outcrops. Depending on climate and environment certain species will thrive, although only lichens can withstand sea spray. Even old man-made walls such as brick and flint can attract small plants (via seed settling in holes) if pointing is missing and there is a reasonable supply of rainfall or water from downpipes, etc.
In urban spaces, a more ornamental, if somewhat artificial version can be created by planting directly into specialised modular panels or pockets that can be installed on wall facades. These allow for a much denser planting than will be found in nature and can therefore be useful in completely covering an unattractive vertical surface such as concrete or cheap brickwork. However they depend on the use of irrigation or hydroponic systems for survival. Whether inside or outside, they are a sustainable way to incorporate nature into urban environments.
Advantages of Living Green Walls
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Improved Air Quality Green walls act as natural air filters. The plants absorb carbon dioxide, pollutants, and toxins, and release oxygen, improving the air quality around them. In areas with high pollution levels, living walls can significantly reduce particulate matter in the air, making urban spaces healthier for their inhabitants.
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Thermal Regulation One of the most important advantages of living green walls is their ability to regulate temperature. Plants on the side of buildings provide shade, and in summer help cool the building by reducing the heat absorbed by the exterior surfaces. This in turn reduces the need for air conditioning and lowers energy consumption. During winter, green walls provide an additional layer of insulation, helping to conserve heat inside.
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Aesthetic Appeal and Well-Being Green walls enhance the visual appeal of any space. Whether they are used to cover drab, concrete exteriors or transform a dull indoor environment, living walls bring a natural, vibrant touch to any setting. Studies have shown that exposure to plants can reduce stress and improve mental health, promoting a sense of well-being. The greenery provides a calming influence in busy, often stressful urban settings.
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Noise Reduction Urban areas are often noisy, but green walls can act as natural sound barriers. The plants and their structures help absorb and deflect sound, leading to quieter indoor and outdoor spaces. This is especially beneficial for buildings located near busy streets or industrial zones.
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Biodiversity Enhancement Living green walls help bring wildlife into the heart of cities. Birds, insects, and other creatures are drawn to the plants for food, shelter, and nesting sites. This promotes urban biodiversity, contributing to the overall ecological health of a city.
- Space-saving Greenery Living walls are a clever way to bring greenery and biodiversity into small city gardens without taking up valuable floor space. They can greatly enhance a short view, especially in urban areas where buildings are close together.
Disadvantages of Living Green Walls
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High Installation and Maintenance Costs One of the main drawbacks of green walls is the initial cost. Installing a living wall requires professional planning and installation, as well as a well-designed irrigation system. Additionally, maintaining a green wall involves regular checks to ensure the plants are healthy, and the system is functioning properly. Watering, pruning, and pest control are just a few of the ongoing maintenance tasks that can add to the overall cost.
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Watering and Irrigation Challenges While green walls are designed with irrigation systems in mind, they still require a significant amount of water. In areas where water conservation is important, the irrigation needs of a green wall may become a concern.
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Weight and Structural Concerns The weight of the plants, soil, and irrigation system can place a strain on a building’s structure. It's essential to ensure that the building can support the additional weight of the living wall, particularly in older buildings or those with limited structural integrity.
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Limited Plant Selection for Certain Climates The choice of plants is crucial for the success of a living green wall. Not all plants are suitable for vertical gardens, and orientation and climate plays an important role in determining what will thrive. Extreme temperatures or harsh sunlight conditions can make it difficult to grow certain types of plants.
- Too artificial? While the greening of any man made wall can be an aesthetic improvement, they can look artificial. At Chalcot Garden Design we aim to create naturalistic landscapes, so when including a green wall as an architectural feature in a garden we would be looking first and foremost at using a natural dry stone wall, partially planting in gaps and crevices with species seen in the local landscape.
Suitable Plants for Living Green Walls
Choosing the right plants for a living green wall is key to its success. Some plants thrive in vertical gardens, while others may struggle. Looking at the natural habitat of a plant species will help to determine its suitability. Here are some of the best plant choices for living green walls:
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Succulents
Succulents are an excellent choice for living walls because they are drought-tolerant and low-maintenance. Their ability to store water in their leaves makes them ideal for areas where water conservation is important. Examples include sedum, echeveria, and agave. -
Ferns
Some small ferns are well-suited for shady, humid environments, making them perfect for a north facing wall. They are hardy and easy to grow - examples include wall-rue ferns and Maidenhair spleenwort. -
Ivy
English Ivy Hedera helix is often used in green walls because of its fast-growing nature and ability to cover large areas quickly. -
Herbs
Herbs like basil, rock samphire, and thyme are for those who want an edible garden. They can thrive in sunny spots and provide the added benefit of fresh herbs for cooking. -
Flowers
Flowering plants like Centranthus, Armeria, Petunia, and Lobelia can add a splash of color to a living green wall. However, these may require more attention, particularly with regard to sunlight and watering. -
Grasses
Ornamental grasses like fescue can add texture and movement and are especially well-suited for walls with sun exposure.
How do modular systems work?
Sturdy metal frames are fixed to the building or other structure, creating an air gap between plants and the wall. A series of plant pockets or cassettes, that hold individual plants are fixed to the frame and supplied with water either by a drip irrigation system, or by a series of gutters that allow plants to draw up the water through capillary action. Behind the system, water will be supplied by a hidden reservoir or even attached to the mains water supply.
Conclusion
Living green walls are more than just a decorative trend; they offer numerous environmental, social, and economic benefits. From improving air quality and reducing energy costs to enhancing mental well-being and promoting biodiversity, they are a testament to how nature can be integrated into urban life. However, they require careful planning and maintenance to ensure their long-term success. By choosing the right plants and locations and understanding the challenges involved, green walls can transform urban spaces into vibrant, sustainable, and beautiful environments for all to enjoy.
