As our green walls change how do we maintain them and ensure their success?  As you may know, "Green Wall" is used as a global term for both living walls and green facades, for definitions refer to “An Intro to Green Walls and Green Roofs: Living Architecture at its Best - Green Walls Part I Nomenclature.”  We will talk about maintenance variables that will affect the changes and the “How To” application of maintaining green walls.

Before we dive right into the maintenance, a reminder that the non-vegetated components, whether part of a soil based modular system for a living wall or a cable / modular trellis system for a green facade, are mechanisms to hold plants in place and to offer the basic needs for plant survival.  Rethink a simple potted plant. (I have referenced this point in other writings.)  The pot, no matter how large or small, clay, plastic or metal, is a holding mechanism for the plant.  Traditionally, the pot is filled with a growing media that can support a root structure, hold nutrients and when placed in the correct amount of light and provided with enough CO ₂ will usually survive.

If the pot contains a plant that needs sun and you keep it in the shade and it does not survive, do you blame the pot?  The point is to choose a plant type that is relevant to the sun aspect and microclimate of the green wall structure and therefore conducive to the environment in which it will thrive.  Back to the case of the potted plant, can we really blame the pot if the plant fails or doesn’t perform?  Or should we rethink our choice of plant material relevant to the needs of the individual plant, its environment and the green wall mechanism?  The point is green walls are simply tools that allow us to host the living plants and help sustain vertical growth, so don’t always blame the system for plant failure: first evaluate the needs of the plants, plan your maintenance and plant characteristics for survival accordingly.  Although not all green wall products are created equal and some do a better job of maintaining plant health, most can be constructed of various materials such as metals or plastics and offer a variety of options including depths, which can all be taken into account by the designer.

That simple statement, “First evaluate the needs of the plant” will lead us to the components for the plants' survival…and ongoing maintenance.  The plant world can be difficult for the untrained botanist, so read the plant tags carefully prior to purchasing or stand by the advice of the green wall manufacturer.  Each plant species has a list of characters that depict what the ideal conditions should be.  Characteristics can be identified as what describes the plant.  It may include phrases such as, “A rapid growing ground cover that can turn red, bronze or brown in full sunlight.”  On the tag look for key words such as “sun” and “water,” “heat and drought tolerant,” “needs constant moisture,” “fast growing,” “potentially invasive,” and “hardiness zone.”  These are very important buzz words that describe the plant, what they need for survival and will define the maintenance needs!    We would have to write a lengthy book in order to decipher all the possible maintenance topics for individual plant types.

With crops, it is uncommon for the wall to be above six feet high so it is easy to work on by standing in an upright position,  unlike traditional vegetable gardening where you are always bending or kneeling.  The green wall panels can also be planted at a height comfortable for almost anyone making green wall panels ideal for healing gardens, assisted living activities, children and other physically disadvantaged scenarios.

We identified the five components to maintaining a green wall to include location, structural inspections, irrigation, drainage and plant maintenance.  Although maintenance is conducive to the plant type, the five headings are common threads to any of the green walls.

Location Access

Location in this sense is defined as the physical area the wall is located.  For example, is the wall behind a secondary structure, is the wall only on an upper location of a building or is the wall fifty feet off the ground?  No matter what the plant type, the first item of consideration is how to access the green wall.  Usually a similar method used during the installation would be ideal.  If the installer used a scissors lift or a man lift the same equipment would be acceptable for major maintenance such as plant replacement and major pruning.  For general service and site visits a ladder may suffice.

Structural Inspections

It is recommended that any of the green walls be approached from a preventative methodology.  The fact of knowing the potential issues that may occur allows planning maintenance around these issues, creating a simple task analysis and level of hierarchal importance.  Even the most experienced installers are not exempt from mechanical failure so check your waterproofing and penetration methods.  In addition, if you are a customer or client of a green wall manufacturer/installer, question these methods and ask for specific details - remember that water will find the smallest penetration.  The structural bracket assembly on some systems is very complex and warrants an in depth inspection, while others are designed with simple functionality allowing for simple physical performance and free water and air flow behind the green wall.

Irrigation

The second order of events is to operate and visually inspect the irrigation system.  Some items to look for include: clogged emitters, leaks at the coupler and connections and small drips within the irrigation manifold.  At this time it is ideal to remove and clean or replace the filter or screen from the drip irrigation system.  This will prevent any sediment from entering the thin tubing of the drip line creating clogs and emitter malfunctions. The irrigation is easier to assess with a trellis or cable system assuming the plant and the root system is at the base of the mechanism used to support the climbing plant.  The irrigation, no matter a bubbler, soaker, drip or other low volume technique, should be working to the original specification.  It is also a good idea to check the mechanical components such as the timer, zone valves, screens and any connections.

Drainage Maintenance

During the irrigation inspection is also the opportunity to check all the connected drains that collect the excess irrigation and rainfall.  No matter the location, interior or exterior, a drain is essential to prevent water collection in the event of a heavy rain or an irrigation failure.  If the irrigation is left on or becomes the victim of a faulty irrigation zone valve, there is the possibility of the water overflow.  The drain acts as an overflow thus inspection of the intake must be part of the inspection process.  Materials such as dead leaves, soil, mud and even public garbage have been removed from the irrigation drains!

Plant Maintenance

The last order of inspection includes the actual plant material.  As mentioned earlier each plant has its own maintenance requirements.  A common maintenance requirement for exterior green walls is to weed the wall.  In this step, the trellis and cable systems are more susceptible to weed growth since the area the climbers are planted is on the horizontal surface.  Unlike the soil based green walls, weed seeds have a harder time rooting on a vertical plane.  Nonetheless, weeding is a common practice in all system types.

Other common practice includes the physical inspection of all the plant material.  The visual health would be obvious - disease, dieback, dead foliage and the noticeable and acceptable levels of overgrown plants.  It is common that some of the indoor plants suffer yellowing leaves that can be easily pinched or some climbers may become woody and can this can be solved by pruning.  It is at this time that the plants can be pruned, trained and cleaned.

Interior plants may require a dusting to keep them healthy.  After wiping any dust from indoor plants, you can also apply a thin coat of a non-toxic plant shine to bring out the plant colors and textures.  This is also the time to inspect for any erosion or media loss and the look of the non-vegetated component of the product itself.  Look for cracking, and in some green walls there is a growth media bag that may require replacing.  On the exterior, the metal-based products are not susceptible to expansion and contraction nor suffer from the heat and cold of the elements and exposure to the sun.    Also during the plant maintenance checkpoint, inspection of the structural integrity of the wall mechanism may be easier.  This is an opportunity to see the internal portions of the green wall that are usually covered by foliage!

Finally, as a miscellaneous item, if the green wall system has artificial lighting this is a good time to check the bulbs for replacement.  With a planned preventative maintenance program the physical structure and integrity should be inspected on a monthly basis.  Irrigation operational failures will be more obvious since the plants will be on the decline, and leaks could become a costly event.

No matter if you are a do-it-yourself green wall owner or a professional maintenance technician and installer, preventative maintenance will retain the safety and integrity of any project, plus add years of sustainable beauty to any wallscape.