Technology, Liabilities, and Growing Media: Change is Good
By George Irwin, The Green Wall Editor
Photos Courtesy George Irwin Unless Otherwise Noted
April 21, 2010 The Green Walls Column Unlike the usual spring article when I'm usually complaining about being busy with tradeshows and with preparation for projects or travel, here it is April and I did not get my first article ready by February as anticipated. I’m much disciplined when it comes to getting things done on time, so I'll blame it on others around me for being so busy. Our colleagues and clients are just as busy. Why is everyone so busy? I’m blaming technology. Before computers, PDA’s, cell phones, mobile Web and laptops, it actually took days to send a letter - now a million letters can
be sent in a single click, and the need for instant gratification sometimes supersedes quality. The rise in technology has brought about change and, in most cases, change is good. Products become better suited and applied, projects become bigger and more intricate. The same is true for green walls.
In January I had a chance to be a guest speaker at the Tropical Plant Industry Exhibition (TPIE) in Fort Lauderdale, Florida. One of the great things about being a speaker is you have an opportunity to walk the tradeshow floor, meet others who are doing research, propagate new ideas, form new relationships, and see new developing products. 2010 seems to be shaping up as what I see as the “Minimal Use Vertical Wall” with a handful of new green wall companies. Nothing bad about having a new company, we all started somewhere, however, not all green walls are created equal. In fact, I have always talked about the advantages of products developed for long term use. Let's face it, there are some materials we don't want, or trust, hanging on walls four stories high, but if you want to dress up your back yard fence with a lightweight option (re-planting them year after year), these minimal use green walls may be your answer. For example, there are plastic bags and canvas pockets that hang from a wall, another one that looks like a baby diaper pinned together, and the ubiquitous upside down tomato growing sock. Yet as green walls become more popular, the projects become more intense, the spectacles become more dramatic - and so can the liabilities. As an industry spokesperson and a frequent visitor to industry shows and events, two of many key questions I always seem to get asked include the liability of installing green walls, and type of growing media for green walls.  | Notice that broken plastic is securing the product to the bracket. |
First let’s talk about liability; here is where we may run into problems with new, unproven companies entering the green wall market. Some of the products offered are for all intents and purposes, bordering on novelty or single season use (use it for one summer and throw it away). For example, some of the products I have recently seen or experimented with are advertising and displaying higher mounting elevations than I would feel comfortable with installing. There are very few commercial grade green wall products with a proven track record that are made to last indefinitely, constructed from materials to meet wind and weight loads, accommodate extreme variances in temperature and to withstand other regional abnormalities (e.g. salt tolerance around coastal regions). Some of these new green wall products, specifically some of the living walls, have no track record at all. Recently I encountered a press release from a “New & Exciting” company introducing green walls. After some in depth investigating and direct knowledge, the company had no track record of manufacturing, installation, training, certification, or a portfolio behind them. Who is qualified to install green walls? According to the Chicago Tribune article "Turf wars, Chicago-style: Roofers vs. green-roof landscapers" of October 2009, the National Labor Relations Board (NLRB) favored the landscapers over the roofers to be capable of installing green roofs at a lower cost, and referring to roofers they pointed out that "they are no less experienced but are more efficient at installing green roofs.”
Green roofs, fine, there is more than enough training opportunities to learn about green roof installations; some companies provide a professional certification course that credits them to be "Certified Professional Installers" for that company's products, and other opportunities are more generalized such as the Green Roof Professional (GRP) accreditation offered by Green Roofs for Healthy Cities. Understandable, and I accept the verdict by the NLRB hands down. I do, however, have to speak openly about landscapers installing green walls. Some of these projects, not all, involve a level of construction not normally associated with traditional ground elevation landscape work. I can freely comment because I was a landscape contractor for 23 years before I, too, entered the green roof and wall arena in 1999.
In comparison to traditional built in place green roofs, for the most part a green roof tray system is relatively simple to install - once on the roof it’s a simple matter of safely getting the trays in position, and adding irrigation - which should be part of the landscapers' knowhow. Overall, most roofers do not have the background or knowledge set to diagnose and treat problems relating to plant health, whereas the landscape contractor is ideal to be the stand alone green roof installer and maintain the vegetation.  | Fig 1. Proper scaffolding is a serious job. |
Not to say all green roofs are that simple, but for this purpose it’s just not the same as green walls. There are no standards for green wall technology, with multiple systems to choose from including green façades and living walls (both growing media based and hydroponic). Each system is different and each manufacturer should provide some type of formal, recognized training for a safe installation and the long term safety of an often large product hanging from a wall. Some construction skills associated with the assembly of such systems require extreme measures necessitating specific training; it’s not about simply screwing brackets to a wall. For example, one of my company's projects, the PNC Bank project in Pittsburgh, PA, left and below (Figures 1 and 2), was prepared by G-Space/ Philly Green Wall and Roof, a skilled, state licensed design/build firm certified under our product's brand, and not installed by landscapers. The vegetation was already mature and grown into the system by a horticulturist and/or a growing facility, and thus did not need the additional plant expertise of an experienced landscape contractor. In this case it wasn't about the welfare of the plants, but the physical installation including engineering, crane operations, calculations, mounting hardware, job site preparation, scaffold safety, fall restraints, etc.  | Fig 2. Prep Work to Accept a Living Wall. |
 | One type of man lift. |
This is not to say this is the norm for all green wall installations. In my personal experience, even the largest of landscape firms we have worked with globally do not have the knowhow, experience, and insurance coverage to conduct a large scale green wall installation over 20 feet high. Yet, it is here I have to cross over the line and lean to the landscapers to rely upon for continuing maintenance procedures. Pending the scope of work construction, contractors are the large scale installation experts, and the landscapers and growers are the plant experts who should, by all rights, also be the maintenance personal. This raises the question about additional liabilities and working with extended heights. May I remind you that the landscaper is not traditionally adapted to working on scaffolds or in a man lift (a machine that is like a boom that carries a person to an elevated height). Green walls provide a new paradigm to the responsibility and job description of the landscape contractor. This puts an even bigger burden on the manufacturers to ensure they provide resources for the maintenance technicians, requiring additional job safety training and new equipment training. There is a place for both the installing contractor and landscape contractor; having a company who can provide a single service is ideal. Experience is a foundation to lean on as a consumer, and “New & Exciting” could potentially equate to “Dangerous & Liable.”
The second question that is always asked when I’m speaking or in conversation is, “What about the growing media?” I always respond, What about it? Fact is, for every company there is more than likely a different method or medium they
grow in. I always use the word green wall loosely and remind people that "green wall" is an all-encompassing term. And growing "media" is the plural of growing "medium," so unless you have more than one type of growing mix within a project, it should be referred to as growing "medium." And when we're talking about growing media, there are two areas to distinguish between regarding placement in a green wall.  |  | Left: Living Wall - Saul Nursery, Alpharetta, GA, Photo by Caroline Menetre.
Right: Green façade - Desert Ridge Marketplace, Phoenix, AZ by Greenscreen; |
If we're defining a green wall as a green façade, the growing medium would be found at the base of a 3-D trellis type structure to support climbing plant material and vines. In this case you should have a growing medium that is rich in nutrients, drains well, and has a pH level to support the type of plant material in its particular location.  | The Musée du quay Branly Hydroponic Living Wall by Patrick Blanc. |
If we're defining a green wall as a living wall, that's a completely different story since there are multiple locations to place the growing media - or none at all. Follow up questions are necessary! So when someone asks me about the growing media used in green walls, first of all I have to politely ask if they're actually referring to a "living wall." In confusion, the general public simply assumes because it's vertical, it's a living wall. (You can read an archive of one of my earlier posts that clearly defines the differences between a green façade and a living wall.) I've found that more often than not, the question is clearly directed towards a living wall. To confuse matters worse, the ever popular work of French botanist and designer Patrick Blanc is defined as a true hydroponic living wall. This means it does not contain any organic growing media; the plant roots are fed with circulating water containing nutrients. The definition of a living wall states that the roots are evident throughout the entire wall, not just at the bottom as found in a green façade. So, in this case, we have two types of living walls - one with a growing medium and one without. Back to the question, What kind of growing media is used in living walls?
Before I answer the question, you have to understand plants require very few things, and aside from sunlight and the availability of water, free drainage is key - the growing medium has to provide the matrix to allow for water to flow freely in order to prevent root rot, promote oxygen uptake and microbial action. Plants also need to have the ability to extend their root system - if you have ever purchased a plant where the roots are wound around the inside of a pot, you know that plant is root bound and would have eventually choked itself to death. A hard clay type of soil would also restrict root development due to compaction and could eventually kill a plant by drowning it.  | Sphagnum Moss Wrapped in Wire Mesh. |
In addition to preparing the medium for plant roots, consider the plant requirements in relation to light, water and nutritional needs. Other than the lighting, which allows for the plant to produce sugars for energy and growth, everything about your plant should evolve around the roots. Using the correct composition of growing medium will strike a balance of air space, water and nutrients - if you have healthy roots you will have a healthy plant, and if you have healthy plants, you'll have a successful living wall. Some of the new designs starting to emerge consist of a variety of wire meshes shaped into forms that contain a 3-D block of sphagnum moss, coir husk or rock wool. Other bagged type systems use or have used anything from peat moss to potting soil to any of the above. The hanging pocket types, or what I referred to earlier as minimal use, suggest employing “a high quality potting soil.” So with three different types of systems, you may have three types of growing media and methods to establish the wall. And not all growing media are equal.
Currently, there are a variety of mechanical means to hold plants on a wall, but I feel the greatest advances in green wall technology are going to be in the growth media field. Rock wool, coco husk, and sphagnum mosses are all very porous and popular in the hydroponic arena. Pros: They allow for drainage, root growth and are lightweight. Cons: They need a constant supply of irrigation and fertilizers, artificial environment regulation (the need to always monitor the pH levels), and there is no beneficial microbial activity, especially around the roots of the plants.  | Top View of a Coco Husk Insert. |
On the other hand, quality potting soil mainly consists of peat moss; although controversial and questioned as being a sustainable harvesting practice since it involves older bog ecosystems, it provides the support matrix needed to sustain plant growth. Media-based living walls were introduced around 2004, and the growing media used was a high quality potting mix. Personally, peat was the base to one of our older medium recipes, with other added ingredients and micro-organisms, which I can’t disclose because of trade secrets. So I know firsthand that the type and quality of peat is of the utmost importance. A newer bog provides a more fibrous peat, which is ideal, allowing the final product to gather naturally to form something like the commercially available pre-casted peat pots. The fiber content in the higher quality media should be above 60%, have a high water retention rate, drain freely, and provide a balanced pH.
But the potting mix media also needed applications of periodic fertilizer. To add additional controversy almost ignored and rarely published, by comparison traditional lightweight extensive green roof media hold minimal nutrients because of the lack of organic material - and the result is the application of synthetic fertilizers to feed the plants. Even though low maintenance, most succulents and traditional sedum still need nitrogen (N), potassium (P), and phosphorous (K), in addition to micro nutrients as part of a fertilizing plan.
When chemicals are not being absorbed, they become part of the runoff in the traditional sense - the fertilizers are now making their way to the waterproofing layers of green roofs and washing into the combined sewers, drainage ditches and into our waterways, no different from fertilizing your lawn. The same is true for the living walls, no matter which growing media is present, fertilizer is going to have to be added and will eventually contribute to runoff.
Recently I became aware of a medium designed from a fermentation process using old shipping containers that is providing high quality fibrous compost with a consistent organic nitrogen content of 3% using chicken manure as the key ingredient. (Chicken manure has been documented to leach into the water table causing harmful effects because of the concentration when not removed or used as a by-product.) The end product results in a concentrated N, P, and K mix enhanced with additional micronutrient rich media, while the process removes 100% of the methane off-gasses.  | Fermentation process in old shipping containers. |
The process creates a compost and bio-fertilizer being used as part of the new living wall growing media. These properties provide a benefit for the green wall and roof market because it will eliminate the use of synthetic fertilizers and it will not leach like the synthetics. There is no runoff so it becomes the organic base to the advanced living wall and roof media, and can be used as a top dressing to all green roofs to replenish the nutrient values. For green walls, a tea comprised of the fermentation is introduced to the irrigation providing some of the highest quality of living
wall media available.
So, what is my answer to the ever popular question, “What about the growing media?” Now you can see why I answer, “What about it?”
Green walls are advancing; the means in which we secure plants to the wall are numerous. The novelty is over and living wall projects are taking on awe inspiring displays of art, function and controversy. And questions of liability, construction, and maintenance are still part of the unknown equation. I know that the skills of many trades are needed and the skill set
needed cannot be seen as a standalone trade.
I believe change is good and advanced technologies will continue to grow, and liability issues will decrease with increasing levels of education and experience. I also believe that the next wave of fertilizer-free growing media for both walls and roofs is close to being commercialized. No matter what, the industry has expediential room for growth and advancements, keeping us all busy for quite a while.
George Irwin, The Green Wall Editor George Irwin is the President and CEO of Green Living™ Technologies, LLC (GLT) based in NY. Green Living™ Technologies is the only U.S. manufacturer of growing media based green wall and three types of green roof systems. Mr. Irwin is a former trainer for Green Roofs for Healthy Cities Green Walls 101.
Contact George Irwin at: GreenWallEditor@greenroofs.com, George@AGreenroof.com, www.agreenroof.com, or 1.800.631.8001.
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