I have been asked to find out how to build a living wall for inside a sanctuary. Any help would be appreciated.
Thank you for giving me the opportunity to research this topic which is close to my heart and interest. There are many strong environmental reasons for installing an indoor living plant wall even beyond improving aesthetics (they are beautiful). Living walls can minimize glare, modify the temperature, filter the air, and reduce ambient noise.
Most of the time, green walls grow tropical plants that tolerate indirect light, such as ivy, ferns, and moss. But they can also grow green edibles such as lettuces and herbs, and could be a source of income, reduce food insecurity, and be a source of healthy food. When exercise is important, a living wall promotes physical activity, and most importantly, as with all sources of nature, a green wall can relieve stress and improve morale.
A living wall is basically a vertically-arranged set of troughs, pots, planters, pockets or trays made of multiple materials including felt or recycled tires, (mostly) resting on ledges, with plants growing in an artificial medium, that are manually or automatically watered. The plants can be started on the wall, but in most cases, plants that have been pre-started in nurseries are used for instant gratification.
There are three broad categories of living walls: a tray system (has the most versatility for small to large systems), a hydroponic system, and felt-pockets. With the tray system (also called a panel system), the plants stay in the pots they were grown in, and rest on a small amount of water (supplied through an irrigation system) that they absorb through their roots. In the hydroponic system, the roots grow behind (and in) a wall of capillary fabric and the nutrients are delivered through a solution mixed in with the water supply. Felt pockets utilize the same basic irrigation set-up as the tray system, but instead of housing plants in their nursery pots, the plants will be planted directly into soil which is encased in felt. Less commonly available are trellis systems, where plants grown in containers are trained (directed) to grow up a wall trellis.
The technology can be complicated or very simple.
Small is beautiful. The simplest design is for smaller units that are free-standing. They do not require either a source of electricity, a tap for water, or a pump. Water is supplied manually, or is pumped up through battery power, and is absorbed by the plants through capillary action. The water can also be supplied through a drip-down irrigation system. They often come in modules that lock together, so it is reasonably easy for you to find one that fits the indoor space you have. They vary in price from $300 to $5,000, depending upon the size and technology.
Larger living walls needs a contractor: If you wish to have your living wall attached to an indoor wall, you have a larger system that, importantly, will require the help of an installation contractor. You will need a source of water for the drip irrigation system and electricity for lighting and a pump. If the living wall is attached to the wall, there will be damage to the wall once the living wall is screwed in. Toronto Master Gardeners do not make recommendations to individual suppliers. Landscape Ontario could direct you to contractors who have experience in this area.
For a wall-mounted living wall, the first layer is waterproofing material, such as 20 mil polypropylene, and then furring strips (strips of wood or another material to raise the surface, provide air flow, and prevent dampness) to protect the wall. The living wall (before you have the plants) will be about 6” from the wall. Once the plants are planted and are thriving, and if there is an irrigation system, the depth to the structure can be to 10-16” from the wall.
Water: Water can be provided to the plants in a number of ways. If the system is small, the plants are watered manually. If larger, there needs to be some form of irrigation. These systems may need a rear drain for drainage, an irrigation feed, and a drip-water assembly. There are alternative systems for top-irrigation, side-irrigation, or bottom-irrigation system. A fourth system uses a sub-irrigation reservoir using simple-felt wicking. The water can be pumped up from a trough below that is manually maintained to seep into the pots, or there are systems that are drip-down.
Light: In most locations, supplemental full spectrum lighting is also required. Even if the living wall is close to a window, there may not be sufficient light in your location to maintain plant health in the winter months. Lights will need to be suspended overhead, about 6” from the plants, or be on the ground facing up to the plants. The lights will need to be on a timer, so the plants are only lit for 12 hours a day.
Medium: The grow medium for living walls is similar to that used in hydroponics – artificial, light weight, and requires fertilizer. In the felt systems, real soil is used with vermiculite and perlite to lighten the medium. This will add weight, but allows the plants to grow bigger.
Plants: Tropical plants are mostly recommended for indoor plant walls, particularly ones that have a wide range of tolerance for low light and moisture. It is important that the selection of plants have similar light and moisture requirements.
Recommendations for plants come from a previous question to the Toronto Master Gardeners on living walls. They would include Aeschynanthus (lipstick plant), Aglaonema, Anthurium, Calathea, Codiaeum variegatum (croton), Dracaena, Epipremnum (pothos), Maranta, Philodendron sp. (heartleaf philodendron), Pilea, Schefflera arboricola, and Spathiphyllum (peace lily). Many varieties of ferns would also be suitable additions: Adiantum (maidenhair fern), Asplenium nidus (bird’s nest fern), Davallia fejeensis (rabbit’s foot fern), Pellaea rotundifolia (button fern) as well as various Pteris ferns.
A list of plants that are commonly used by one company include: Aglaonema – plants such as Green Lady, Silver Bay and more; Epipremnum – also known as pothos; Philodendron – vining and non-vining varieties; Dracaena – such as Lemon Surprise, Dorado, Green Jewel and Jade Jewel; Spathiphyllum – sometimes just called “spats”; Syngonium – in particular nephthytis in dwarf varieties; Calathea; Maranta; ferns – a number of varieties work well in Green Walls; Schefflera arboricola; Ficus repens – sometimes referred to as creeping ficus; crotons
Another company lists these plants as good suggestions for living walls: Philodendron, Neon/Golden pothos, White Butterfly nephthytis, Schefflera ‘Luseane’, Ficus elastica, Pink Syngonium, Austral Gem fern, and Anthurium.
It is also possible to grow leafy edibles on a living wall such as lettuces, microgreens such as cress, swiss chard, and herbs. Some people are growing beets, carrots and onions to harvest their leaves, and even cherry tomatoes.
Disadvantages: The biggest disadvantage to installing a living wall, is that at this time, they are expensive. Lets Talk Science estimates that they cost $900-$1,500 per square metre. They also note that living walls require constant, ongoing maintenance: a living wall can grow 50 plants per square metre. The maintenance should include misting if the room is dry, and regular cleaning and wiping off any traces of dust or insects. The major problem with the plants will often be overwatering, which can lead to plants dying and mold growing. Therefore it would be good to invest in a fan to increase air circulation.
Further Information: The Australian online university offers a course in vertical gardening that is a 50-hour asynchronous course available to people not living in Australia.