Living Wall Breakdown -
Material & Flora Relationship


By George Irwin, The Green Wall Editor
The Green Walls Column

Photos Courtesy of George Irwin Unless Otherwise Noted.

Millions of hard working people could more than likely agree that the one thing we wish we had more of is time.  Seems like my articles are becoming annual occurrences without any planned calculation of a new topic.

This time I had a purpose to delay a new publication.  I did some self-reflection of my personal and industry contribution to green roofs and living walls and for a while thought about stepping down from my contributing articles and what fun would that be, since most of you reading could honestly say I do not lack controversy and I call it like I see it since I started writing for in March of 2008.

For the last year I have become frustrated with the lack of quality and increased failures.  I have addressed countless failures and requests by competing clients willing to pay me for help on their current living wall.   Over the past year I believe too many living wall companies or manufacturers have been putting products in the market that are creating more problems than solutions, eventually creating some interesting and controversial discussions in social media.

There is a quiet whisper the industry is not revealing - that there are more failures than successes in the living wall business.  Personally, I have hundreds, if not thousands, pictures and emails asking me to help fix others' living walls.  I’m humbled they seek me for help and frustrated because the only solution is to educate them on the type of system and why it keeps failing.  Insanity is doing the same behavior and expecting different results, right?  In the living wall industry you can’t keep replacing plants without changing the variables: something is causing these plants to fail.  Rhetorically speaking, is it temperatures?  Nutrients?  Anaerobic conditions?  Lighting?  Poor drainage?  Or a combination of all of the above?

1886 is regarded as the birth year of the modern car.  German inventor Karl Benz built the Benz Patent-Motorwagen.  I hate to reference Germany because I know my friend Jorg Breuning will have a snicker and remind me that “He is German.”  It’s only funny if you know Jorg and it's all in good fun as he is well respected.   Vehicles were first powered by steam then internal combustion and now electricity.  The introduction of vacuum tubes, sensors, material quality, assembly, and modern technology have changed the automobile incredibly.

Previous articles focused on the “How To” of Living Walls; I want to get away from fueling the industry with advanced techniques and instead focus on some of the reasons living walls fail.  The living wall industry is still in its modern infancy.  Growing quickly, we can trace its history from the Hanging Gardens of Babylon through the first organized farms in Turkey to the Romans growing grapes on trellises to their marketing by way of the notion of the “Ivy League.”  Coined by Henry Woodward, a sports writer, to describe a group of universities known for the ivy growing on their walls, the term also signifies higher learning with an elite education status.

"Nassau Hall, Princeton" by Smallbones, cropped by Inabluemn.
Licensed under CC0 via Wikimedia Commons.

For the most part living walls are made up of hydroponic or media-based technology.  You have the option of felt or fabric type layers or a modular application made of plastic, metal, or a combination of both.  Like a car, you have wheels, a steering column, a frame, etcetera.

Living walls have basic components too, like a car, and they are nothing more than the physical structure necessary to hold plant life in the vertical plane.

Notice I said “hold” and not “support” plant life, because in fact some of these materials and assemblies are the reason for plant failure.

There are two types of living wall failure:

1. Material breakdown

2. Plant mortality

a. Cultural reasons
b. Physiological – disease, old age

What caused my living wall plants to die?

Poor material choices, poor design, and poor environmental factors will contribute to the failure of biological processes required for plant survival.  Environmental factors can be changed and monitored.  The materials and product assemblies are critical elements that also impact the end result.

Plants die from cultural and physiological causes.  For purpose of this article I’m speaking specifically about living walls.

For example, we know plastic is subject to expansion and contraction; for years I have personally documented both green roofs and living walls that have used certain plastics which  have been subject to falling off the wall or were a breach threat to a waterproofing green roof application.  Does that mean that all applications using  plastic will fail?  No, of course not.

We also documented felt-like and fabric-type living walls that are subject to algae build up, material breakdown, and anaerobic conditions.  If the living wall materials break down, they will eventually contribute to the mortality of the plants by its inability to maintain the structure and by the contribution to anaerobic activity.  This statement holds true for any material.

Material breakdown showing signs of algae build up contributing to the lack of oxygen at the root level.

Cultural causes are something that happened or are happening to the plant that it (the plant) didn’t agree with.  I have documented plants dying after being accidently sprayed with cleaning solutions or as a result of over fertilizing.  Plants are also subject to temperature changes, light, or the lack thereof.  (Read my article How Important is Lighting for Living Walls? via my archived column.)

In extreme incidents living wall plants may fail due to under watering.  This situation would be more prevalent in media or soil type systems where there was inconsistency or more likely a mechanical failure within the irrigation or failure to attend to the irrigation.  In simple terms too little water means the plant will be deprived of nutrients; it will dry out and usually never recover.  Note that living walls are also subject to drying out because of wind or heat vents - this situation is preventable from a designer with sound living wall experience.

"The fancy watering system has never quite worked.  Either it overwatered or it underwatered the plants," said a local councilmember in the London Evening Standard, 2009.
Photo: Architects Journal.

Under watering is rarely the case in hydroponic type walls simply because of the nature of the system.  The number one reason for plant mortality is overwatering, which is is a “cultural cause.”  The majority of references about plants will be attributed to “overwatering” vs. under watering as the single most common reason of mortality - here are a few:

“Overwatering can lead to a plant’s roots not receiving enough air, causing the plant to suffocate. It can also lead to root rot.” ~ Spring River Nurseries

“Overwatering is far and away the most common reason for house plants to die off. Even if the soil at the top of the pot is dry, there may be a layer of water under the surface, around the roots. If this water cannot drain away or evaporate it will slowly ‘suffocate’ the plant, starting with the fine hair-like roots that do most of the actual nutrient and water gathering, but moving onto the sturdier bigger roots.” ~ Homegrown & Healthy

“Plant leaves that are yellowing or washed out are usually caused by lack of nutrients, over-watering, or poor drainage.” ~ The Home Depot

Effects of over-watering.  Read my "Hydroponic Living Walls – Irrigation" from June 2013.

Overwatering living walls is a tricky subject guaranteed to create some controversial discussion -  I’m going to offend someone, but the truth is the truth, get over it.  We can’t point out specific products, yet not all living walls are subject to the same scrutiny.  Overwatering is subject to:

1. Poor irrigation management.  There is a fine line between quantity and quality.

a. Timer may run too long.
b. Maintenance may not adjust quantity for seasonal use.
c. Poor system design where the upper portion of the wall is dry in compared to the lower portion.
d. Wall is not zoned correctly.

2. Materials used to create the living wall, the assembly, and configuration of the materials.  Poor drainage may lead to excessive water retention.

a. Felt is notorious for absorbing water so care must be taken to not over water.

3. Ensure the product chosen meets structural demands and will not degrade under physical or environmental pressures.

In overwatered conditions, the spaces between the roots are filled with water so the oxygen supply is almost completely deprived.  As a result, plant roots cannot obtain oxygen for respiration to maintain their activities for nutrient and water uptake.  Plants weakened by lack of oxygen are much more susceptible to diseases caused by pathogens.  Lack of oxygen at the root level causes death of root hairs, reduces absorption of nutrients and water, increases formation of compounds toxic to plant growth, and finally retards growth of the plant.

Overwatering can also be contributed to the lack of light, usually a situation created by an inexperienced maintenance technician who lacks the ability to recognize that low light equals less water.  Photosynthesis cannot take place without adequate light.

La Mar Green Wall in Miami with LED Lighting.
See my "
How Important is Lighting for Living Walls?" of June, 2014.

In one of my previous articles I note low light levels mean low levels of photosynthesis.  This lack of light is a trigger for a chain reaction through the plant causing evapotranspiration which impacts the inability for nutrient uptake by the plant.  The plant's metabolic function slows down, and is unable to engage in the photosynthesis process.  When the plant function slows down, the requirements for water and nutrients are also diminished.  This is a critical stage in which most overwater their plants and cause root rot, and pathogens and fungus gnats are present.

In contrast to cultural causes, diseased and aged plants are physiological causes and involve something within the plant to break down.

Excessive salt and fertilizer build-up.

Physiologically speaking...usually we direct our attention to old age.  Very rarely do plants reach an age of mortality before some type of cultural practice results in a physiological death.  For example, over fertilizing plants creates a buildup of salt causing a reverse action of drawing water out of the plant causing it to burn and die.  The same happens when you over fertilize your lawn or spill fertilizer in one spot.

How to Avoid Living Wall Failure?

Choose an application that will meet all the criteria for plant survival.  The choice of materials will impact the success or failure, and there are environmental factors that need to be planned well in advance.  Choose materials that drain freely and prevent the “sandwiching” of the root system.  This is where the anaerobic conditions are most prevalent.

Here is the environmental checklist that will help in the survival of the living wall:

1. Use likeminded plants that require the same maintenance needs.
2. Key common elements: Water, light and nutrients.
3. Quantity and quality of the key elements are compatible with plant choice.
4. Choose plants conducive to the existing environment or prepare to amend the environment.

a. Do you have to add lighting?
b. Is there a door nearby that may impact the immediate temperatures?

5. Provide proper ventilation.

Physical Characteristics for Living Wall Materials:

1. Material not subject to breakdown.
2. Drains freely.
3. Won’t hold excessive water.

In an industry with a resemblance to the gold rush where everyone is trying to be first and get a piece of the pie, the experience in the recent years has blossomed to uncertainty amongst certain applications, confusing to, and at times duping, the end user.  No matter my opinion or documented fact, there is a sense of urgency to be controversial and argumentative about living wall products.

I have a comfort level with my own research and understanding of plant material and the data I have collected over the years to know the information provided is broad yet accurate enough to bring to light the issues facing the living wall industry.

The future of living walls is very much alive, but I believe only a few types will truly thrive, continuing to provide change and improvements.  Those which lack change and improvement will fall to their own fate while others that flourish will continue to educate the end user, bringing light to the advances and scientific breakthroughs of living wall technology.

George Irwin, Green Wall Editor


Greenhouse Glazing & Solar Radiation Transmission Workshop, October 1998 © CCEA, Center for Controlled Environment Agriculture, Rutgers University, Cook College.

Publisher's Note:  Join us at the Greenroofs & Walls of the World™ Virtual Summit 2015 ~ Connecting the Planet + Living Architecture starting on April 6 through May 31, 2015.   George Irwin will be a member of the "Social Healing with Greening" Panel with Patrick Carey (Moderator), Peter Ensign, and Darius Jones.

George Irwin is the Founder and president of Green Living™ Technologies International (GLTi),  based in NY.  He manufactures the patented Green Living Walls, Green Living Roofs and is a global pioneer in Vertical Agriculture.  A published author, and featured as the “Green Wall Editor” within the industry, George is also a leading resource and authority for green wall and roof technologies around the world.  TIME, Fortune Magazine, Profit Mag., CNN, NBC, Good Morning America & Newsweek are among the major media recognizing GLTi and the use of his technologies.

Contact George Irwin at:,,, or 1.800.631.8001.

Past Green Wall Articles

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