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SOME of my favourite writing spaces of late have had a – a vertical garden of plants – or a bountiful green roof. There is something very soothing to me about being in a space with a visible, robust community of plants.

Green roofs aren’t new: they have been reported to exist as , in the Hanging Gardens of Babylon. But they appear to have become more common recently, or at least my noticing of them has become more frequent. I have seen them at hotels, restaurants and my current and former workspaces.

Living walls and green roofs are composed of plants growing in soil or in a hydroponic system, which is a method for growing plants in a water-based nutrient solution. often feature on living walls, while that can resist dry conditions are prevalent on roofs.

Living walls can be found indoors or on the outside walls of buildings. They can also be installed in or on commercial buildings or, at a smaller scale, in homes, with herb gardens being a popular choice for homeowners.

Given the vertical nature of growth, living walls often have an integrated watering system that is designed to add to their eco-sustainability. They improve air quality by taking up carbon dioxide for photosynthesis and releasing oxygen.

Outdoor living walls also help with insulation and temperature control and, like green roofs, will contribute to sustainable drainage by absorbing the rainwater that could otherwise run into storm drains and increase flooding risks.

Living walls’ greatest attribute, though, may be aesthetic: they are living pieces of art. And this is art that has a health benefit, not only because plants provide oxygen and filter water, but because engaging actively in plant care can .

Green roofs, meanwhile, can have both economic and sustainability benefits. Their plants grow in a substrate, such as soil, placed over a waterproofing system or in containers. This helps to provide protection against exposure to wind, excess light – including damaging ultraviolet rays – and surplus water. They may also serve as in more densely populated areas.

One of the most frequently advertised benefits of green roofs is the energy efficiency that they add to buildings by serving as insulation. By limiting heat loss in winter and absorbing sunlight in summer, they reduce the need for air conditioning and heating, and thus save money.

Green roofs are also reported to act as fire retardants, which may lead to their increased use in places such as the western US, where wildfires have been steadily increasing in frequency and intensity.

Although they are found at greater scale on commercial properties, are also growing in popularity for homes. Costs for home installation vary depending on the types of plant selected. On top of this, not all walls or roofs are sufficiently structurally sound to have such greenery installed. Green roofs, in particular, may need structural reinforcement due to the extra load produced by substrate, water and containers, which brings additional costs.

Living walls and green roofs also have ongoing costs for upkeep – both financial and labour – that should be considered. Living walls, for example, have lifespans of 10 to 15 years before they need to be replaced, which depends on their substrate, what their plant life cycle is, their size and their mechanical components.

Both green walls and roofs require significant tending to ensure that their plants’ roots don’t escape from the soil or their hydroponic systems. Roots have an uncanny way of growing through things that seem impenetrable, like walls, bricks or pipes, so without proper care there is the potential for . This means that plants with shallow or fine root systems, such as the Pothos and sedums I mentioned earlier, are excellent choices.

The moisture associated with plants in living walls and green roofs must also be monitored to ensure that it doesn’t cause damage to structures, as green roofs can be more susceptible to leakage. As well as structural work, and the necessity of limiting root-related damage, green roofs also need landscaping care and regular watering to remain healthy and nurtured.

While there are potential drawbacks, in most cases the benefits of these burgeoning green spaces outweigh the challenges, in terms of both their ecological implications and the joy that having a thriving community of plants can bring. Living walls and green roofs are a welcome addition to support people’s health and well-being.