The green wall: the origins and the technique
Recognized scientist, Patrick Blanc, researcher at the CNRS and doctoral student in biology, developed the plant wall. His first patent for his green wall design technique date from 1988. After several years of observation in a natural environment, Patrick Blanc, at the end of the 80s, realized that in order to thrive, plants do not have not necessarily need land, but simply of a stable surface allowing the roots to settle. For their proper development, they also need the water, from nutritional elements, such as mineral salts, which added to the ambient carbon dioxide will be able to nourish each plant thanks to the photosynthesis.
In nature, we also find plants which thrive on rocks, tree trunks, etc. Based on these principles and taking inspiration from nature, it is therefore possible to green all vertical surfaces that we want, like the facades of buildings, a terrace wall, balcony, among others. The result obtained is not only aesthetic, but also has a dimension ecological. In addition, the infrastructures thus kept in the shade benefit from a longer lifespan, without forgetting that a green wall constitutes a very good thermal and sound insulation.
In general, the installation of a green wall is done on a support which makes it possible to separate the frame. This support is installed on a metal frame and consists of an expanded PVC sheet as well as an irrigation sheet. A light layer of substrate is implanted over the entire surface. Finally, the plants are placed vertically and colonize the surface. The choice of plants must be considered based on the available light, but also on the climatic conditions to which the wall is exposed.
Create a green wall outdoors: the steps
You wish create your own green wall ? To start, don’t be too ambitious! It is recommended start with a small space even if it means expanding it later. In this way, you will be able to adjust the space, the plantings, etc. over your discoveries and get your hands dirty. Several solutions are available to you :
- You can opt for modules which are sold as a kit in garden centers and that it suffices to fill with substrate. Some even have an integrated irrigation system. If you want a simple, out-of-the-box solution, this one gives you everything you need to get started on a reasonable scale.
- You can also build by yourself.
If you opt for the second solution, it is essential, before you start, to think about design and of make plans. You also need to determine which plants you want, but also where the best location for them is. Here’s how to create your green wall:
- Start with create a frame with planks in Douglas fir.
- On the back of your frame, install cleats to create an empty space between the wall and your future green wall. This space should have a depth of about 5 cm to allow good ventilation of the wall. Depending on the nature of the wall, you can also use metal Omega profiles, but be careful, because these are very heavy, or aluminum angles.
- Once your frame is finished, over the entire surface, you can fix horticultural felt with spikes or staples. This material has advantages such as strength, rot-proof, breathability and hydrophilicity.
- You must then fix a second layer of horticultural felt to create kinds of culture pockets. It will then suffice to make slits in each of them.
- You can delimit each space using staples, for example.
- Install your frame on the wall by fixing it securely. Be sure to choose the fixing system according to the type of wall. So, if your wall is hollow, you can use Molly anchors or chemical sieve anchors. If, on the other hand, your wall is full, you can bet on chemical anchors, or plastic anchors if your work is small.
- Everything is ready ! You can then take care of the filling the pockets with potting soil of good quality potting, but also sphagnum, a kind of moss that provides plants with nutrients and water reserves. However, this is not the most interesting solution because of its ecological impact.
- You can finally install your plants in each of the pockets.
For the choice of plants, you can, according to your tastes and your requirements, you can opt for climbing plants, aromatic plants, strawberries, salads, perennials which will come back every year, etc.
If you want to create a green wall on a large facade, it is recommended to go through a professional who will take all the elements into account.
His maintenance
When all the conditions are met, the lifespan of a green wall is on average 10 years. But you will not achieve such longevity or keep it all its beauty without regular maintenance over time and over the seasons. Here are a few tips :
- Remove as you go wilted or damaged parts of plants. You will thus avoid contamination problems in your green wall. This is why it is important that your wall remains accessible fairly easily.
- Each year it is necessary to change some plants. This corresponds to between 10 and 20% of all plants and varies depending on the plants chosen, but also on their development.
- Prune the plants that require regular pruning.
- Think about water each plant according to their water requirement.
- For an exterior wall that does not require too much maintenance, choose hardy species with evergreen foliage.