Paysalia is one of the main trade exhibition events for landscapers, Over 3 days, they gather, meet, discuss and build the future of the profession together.

At Paysalia 2017, which was held in Lyon, France at the beginning of December, EILO chairman Benoit Pelleriaux, held a presentation.

The next edition of Paysalia will be held at Lyon Eurexpo from  3, 4 and 5 december 2019.

Plants can talk. For a long time, that belief was dismissed as woolly nonsense. But the more we come to know about plants and their properties, the more scientists are becoming convinced that plants really can communicate. And they do that quite ingeniously. Plants pick up signals from their surroundings, process that information and convert it into solutions to enable them survive. As Darwin would say: plants are intelligent. Plants and people actually have surprisingly much in common.

Plants are often deemed the lowest in the ranking of living organisms. Many languages have such expressions as ‘vegetating (like a plant)’, meaning leading a meaningless, soulless life. Yet even in ancient times the question of whether plants ‘had souls’ was much discussed and over the centuries various philosophers and scientists have repeatedly claimed that plants are social organisms and attributed them with certain skills. Until recently, however, this could not be proven and their claims were dismissed as figments of their imagination. Or as science fiction, like in the well-known film Avatar where the inhabitants of Pandora, a planet in the distant future, believed neuron-like electrochemical connections existed between the roots of trees and plants, which collectively formed a nervous system that covered the entire planet, and had a consciousness. Gaia 2.0.

However, recent years have seen the publication of ever more studies which establish the intelligence of plants on the basis of extensive and serious scientific research, and even the emergence of a new field of research: plant neurobiology.

The advantage and disadvantage of being rooted

One of the main differences between plants and humans or animals is the the first group cannot move. If we are hungry we go looking for food, if we sense danger we run away or make a loud noise. We move house if we think we could find a better job elsewhere or when adventure beckons. Plants cannot do any of those things; they are rooted, bound to one spot and therefore completely dependent on their environment. In order to survive, therefore, they had to develop other, sensory mechanisms. And they did. These mechanisms are now known to be highly complex and refined.

Brilliant Green

One of the strongest advocates of plant intelligence is plant physiologist Stefano Mancuso of the International Laboratory of Plant Neurobiology. In the book ‘Brilliant Green’ he and his co-author, scientific journalist Alessandra Viola, reach the conclusion that plants are actually even more intelligent than humans. Whereas we only have five senses, they have more than twenty. Which they use very efficiently.

One of the key characteristics of plants, according to Mancuso and Viola, is that they have a modular structure. That is to say that while each part of a plant is important to its survival, it is not indispensable. The vital functions of a plant are not centralised in single organs; the whole plant functions as a kind of super organism. Some plants can be almost completely eaten away yet still recover.

Advanced senses

Plants can ‘see’. Light, the main ingredient of their energy diet, is vitally important. Not only are plants able to capture and utilise light; via light receptors, found all over the plant but especially on the leaves, they are also able to recognise the quality of the light and to adapt their growth habit accordingly.

Plants can also smell. Plants are covered with receptors for volatile substances. They transmit a chain of signals, passing on information to the whole organism. Plants use ‘scents’ or chemical compounds to interact with their surroundings and with insects. They absorb messages and also release them, when they are exposed to stress, for example. A plant that has been eaten into, will disperse molecules to warn conspecifics in its vicinity of the danger. These neighbouring plants will subsequently produce chemical substances to make their leaves inedible or toxic. The senses of smell and taste are just as closely related in plants as they are in humans and animals.

Plants can taste. In plants, the organ of taste consists of receptors for the chemical substances they feed on. The roots search for these substances in the soil. Plants taste nitrates, phosphates and potassium with their roots, and can locate minimal quantities even at long distances. They do this by allowing their root system to keep growing until all the substances have been absorbed. If the roots encounter substances which are toxic to the plant, however, they will move as far away from them as possible.

Plants also have a sense of touch; such as the well-known ‘touch-me-not’ whose leaves close when touched. It is interesting that this does not happen if a drop of water falls onto it and that the leaf will open again if a stimulus is not or no longer dangerous. Carnivorous plants only close when certain insects land on the leaf, other plants trap insects until they are completely coated in pollen and then they release them again. Many plants demonstrate their sense of touch by winding round objects, enabling them to grow vertically.

Plants can also hear. That is to say: they sense sound vibrations. And they respond to them too. An Italian winegrower, for example, grew his grapes to the sound of music. The results were astounding: the grapes grew faster, were healthier and tasted better.

Plants have developed many more senses besides these five; senses plants can use to their advantage because they cannot move. Senses which enable them to measure the moisture content in the ground, sense gravity and electromagnetic fields, and recognise and measure numerous chemical gradients in the air or soil. All aspects that are essential to their survival, growth and development.

Plants make use of electric, hydraulic and chemical signals to communicate both internally and externally. And make decisions accordingly. For example, in the middle of a hot day, plants can decide to close the stomata on their leaves. This stops them from photosynthesising. But it also stops them from dehydrating,  which then takes priority. They communicate externally by touching each other’s roots or leaves, for example, or by emitting molecules that contain information. Based on that information, a plant may decide to act hostilely or rather to form a symbiosis. Plants also communicate with animals, by producing an attractive or repulsive scent, for instance. Which they can do very cunningly. They are capable of emitting chemical substances that will attract their enemies’ enemies, such as a mite which will eat the mites that attacked the plant. Of course, their scents and colours also enable plants to attract insects and other animals in all kinds of ways, which then act as ‘pollen courier’. Thus ensuring their survival in another spot. Scientific journalist Michael Pollen described it poetically: ‘bees are the legs of plants’. The medium of exchange is usually nectar but some plants are even capable of fooling their visitors by changing shape, scent or colour. There is actually an orchid that can change to resemble a female insect ready to mate. So plants continually make decisions that can influence life or death.

The wood wide web: the benefits of exchange

Practically all plants have intimate relationships with fungi through their roots. Hyphal threads in the soil digest dead animals and plants and release this to plants in the form of carbon. In return, the plants provide the fungi with sugars. Both prefer to exchange with whichever gives them the most in return. So they make choices. The gigantic underground mycorrhizal network that interlinks plant roots, and can be many kilometres in diameter, is nicknamed the ‘wood wide web’. Plant biologist Suzanne Simard of the University of British Columbia, discovered that trees communicate with one another via fungi and that they share carbon and other nutrients with one another, even between different species. Birch trees exchanged CO² with spruce and at a different time in the season the same thing happened in reverse. She also discovered the important role ‘mother trees’ play in this web. These larger, older trees are the hub of the web, as it were, and control the nutrients of the whole network. Simard also discovered that mother trees feed their own saplings more carbon than other trees. It even appears that mother trees that are on the point of dying send extra carbon and defence signals to their saplings via the mycorrhiza network.

Plants as social organisms

Simard’s standpoint that forests are not merely collections of individual trees but resilient, social communities, is endorsed by former forester Peter Wohlleben. One day in the forest he discovered remarkable gnarled specimens, which at first sight resembled lifeless stones but were in fact the remainders of an ancient tree trunk that had been felled centuries ago. To his utter amazement, they turned out to still be alive, despite having no leaves and photosynthesis consequently and the uptake of nutrients thus being impossible. Further research revealed that the remainders were fed by the surrounding trees, via the roots. Apparently the forest would not benefit from losing these weaker members. For Wohlleben this event sparked a continuous fascination for the behaviour of trees.

Wohlleben describes trees in human terms; they can suffer pain, make friends, raise their children, collaborate, sorrow. They give each another space – a phenomenon so poetically described as ‘crown shyness’ – or shade, so that saplings can grow at the slow rate that is best for them.

His book ‘The Hidden Life of Trees’ was a bestseller in many countries. Wohlleben now manages his own forest, where trees are allowed to grow entirely as they please and where he gives people guided tours to introduce them to the wonders of the wooded world.

Do plants justice

That is perhaps the crux of the matter. Inspired by their fascination and wonder, Mancusco, Simard and Wohlleben are all passionate advocates of a different approach to the plant world. Based on the concept of symbiotic communication between plants, enabling a positive development of the whole ecosystem, we should show more respect for plants. And adapt our relationship with them and thus with the planet. Not only would that be more sustainable, it would also be in our own interest.
After all, plants, which account for 99% of the biomass on Earth, form the base of the food pyramid, give us the oxygen we breath and the energy we use, and mitigate the consequences of climate change. On top of which they are also able to detect and tackle substances that are harmful to us or to provide ingredients for medicines. As Mancuso and Viola maintain: the planet will survive without us.

The question is: will we survive without plants?

Plants purify the air

Do you have many plants in your home? Besides being beautiful to look at, that is also very healthy. You would not think so, but volatile organic compounds (VOCs) such as benzene and formaldehyde are very common in the home. These toxic substances are found in clothes, furniture and carpets, for example, as a result of which the air quality in houses, offices and schools is often very poor. This, in turn, can cause poor concentration and headaches. It is therefore vitally important that we make our indoor climates healthier. Plants can help us do just that. Plants are known to be able to absorb these toxic substances and thus purify the air. Our waste consequently feeds our indoor plants and they give us our oxygen and clean air in return. How do plants do that? Where are the filters in a plant? Are they in the foliage, the stems, the roots, or is it the work of another, as yet unknown force?

How do leaves and stems purify the air?

For a long time, research primarily concerned the aerial components of plants. Researchers discovered pores in the leaves and stems of plants. These stomata on the foliage absorb toxic substances out of the air. The more stomata, the higher the plant scores in terms of air purifying qualities. This Egyptian study from 2012 reveals The Spider plant (Chlorophytum comosum) and Peace lily (Spathiphyllum) to be particularly good at absorbing volatile organic compounds from the air with their stomata, for example. Some plants even adsorb small quantities of certain toxic substances in a waxy film on their leaves. In short: above ground, plants can convert significant levels of toxic substances.

However, plants consist of more than foliage alone. In recent years, more and more researchers have also been looking below ground and examining the plant’s thus-far hidden air purifying qualities. It appears that the roots purify the air by absorbing a little of the toxic substances. However, it is primarily the bacteria and fungi living around the roots (the micro-organisms in the rhizosphere) that work themselves crazy to convert the majority of the toxic substances to harmless compounds.

Soil life as air purifying champion

In a South-Korean study from 2008 into how aerial and root-zone parts of plants contribute to the removal of formaldehyde, two species of pot plants were compared day and night. The plants were placed in sealed chambers, where they were exposed to a specific quantity of this toxic substance. The below-ground plant components, the root zone, proved by far to absorb the most toxic substances. This is because the micro-organisms in the root zone do not only work in daylight; they carry on working through the night. While a plant’s leaves take a nap, so to speak, the fungi and bacteria in the soil continue to purify the air. In other words: in daylight a plant’s leaves are also hard at work and soil life then counts for 50% of the air purification (1:1). The night-time ratio is very different, however. The leaves then do practically nothing at all whereas the micro organisms in the soil carry on working just as hard, if not harder.

Bacteria everywhere

This night-time working of bacteria was not the only interesting discovery about soil life. Research by Wolverton in 1993 revealed that the longer the microorganisms are exposed, the more they improve their detoxifying ability. So not only do they work 24/7, they also improve their ability to remove toxic substances from the indoor climate.

Some bacteria do not actually purify the air themselves; they help the plant to degrade the toxic substances more effectively, as it were. Other bacteria do degrade the toxic substances themselves. As many as 7 different bacterial strains were found on the Golden Pothos plant, for example. One of these bacterial strains proved capable of removing 86% of the toxic substance formaldehyde from the air within 24 hours.

Plants and microorganisms live in mutual dependency. The plants supply the bacteria and fungi with sugars and the soil life supplies the plants with minerals and other nutrients in return. Plants secrete a certain sap that attracts bacteria, which is why between 100 and 1000 times as many bacteria are found in the rhizosphere than in soil with no vegetation. This applies to the soil in your garden, but also to the potting soil your indoor plants are growing in. Furthermore, these saps encourage bacteria in the rhizosphere to improve the biodegradation of soil pollutants.

 PM: Particulate Matter VOCs: Volatile Organic Compounds IAP: Indoor Air Pollution Source: www.mdpi.com

Did you know that bacteria do not only live below ground but that the stems and leaves of plants are also covered with these invisible air purifiers? In 2015, a Belgian-Polish study specifically examined these air-purifying interactions between plants and microbes. The researchers concluded that there is tremendous unused potential in the symbiosis between plants and such microbes as bacteria and fungi. They called this purifying effect of plants phytoremediation: the use of plants to clean up contaminated sites.

How does phytoremediation work?

There are several ways in which plants and their soil life can purify their environment. Some plants are capable of absorbing harmful chemicals from the ground and groundwater and removing or converting them. Other plants can purify water or air.

Diagrammatic representation of microorganisms working on or near a plant to purify the air: phytoremediation. (source: www.mdpi.com)

Plants can help reduce contamination through various natural processes:

• Plants can immobilise pollutants in the roots, stems and leaves (photostabilisation).
• They can convert harmful substances into less harmful substances inside the plant or in the rhizosphere.
• They can convert harmful substances to gasses which they release into the air.
• They can immobilise harmful substances on their roots, where they are then broken down by micro-organisms such as bacteria and converted to less harmful substances.
• Plants and their bacteria are also able to absorb volatile organic compounds from the air, thus improving the air quality.

Source: https://clu-in.org/download/Citizens/a_citizens_guide_to_phytoremediation.pdf

Back to indoor plants

Potted plants do not usually come into contact with contaminated ground or groundwater. Most important with regard to the indoor climate, therefore, is that the last natural process of phytoremediation is applied: air purification. Soil life is essential to this process.

A plant living in symbiosis with certain bacteria and fungi can contribute significantly to clean air and a healthy (indoor) climate, and to clean soil and water as well. The foliage, stems and roots all do their best, but really good results are not achieved until the fungi and bacteria join in the process. Microorganisms such as bacteria, both below and above ground, are the absolute champions in detoxifying their environment. Phytoremediation is consequently a promising technique used to remedy contaminated environments; both indoors and outdoors.

Green walls are available in all shapes and size these days. They have a positive effect on the air quality and the surrounding atmosphere. For the construction of such walls there is usually a budget is planned. Maintenance however, is much less thought about. Yet it’s essential to make sure these walls keep looking good for quite some time. Depending on the type of wall, maintenance can be rather simple. Yet for some walls we have to rise to great heights….

Constructing a green wall

Smaller walls can usually be made from one piece. Walls that are larger than two square meters often consist of multiple segments; so constructing them in various shapes and sizes is possible. One segment – or module – is a frame or construction made of sturdy plastic pots, containing the substrate in which the plants can grow. Another possibility is a sort of mat or structure on which textile sacks are fastened where the plants are put in. This method is somewhat more fragile.

Example of modules for a larger green wall

Maintenance of the water supply system

Green walls can be irrigated with various watering systems that can be partly or completely automated. Or you can water the plants by hand. With an automated watering system it’s important that you also have a maintenance contract with the supplier, so it can be checked regularly and fixed, if necessary. Hose, pump and gutters need to be kept clean to prevent clog-ups. Turning the water supply up or down, in summer or wintertime respectively, is also needed because the demand and the amount of evaporation differ with each season.

If the plants are watered by hand, the construction will also need maintenance but simpler. Choosing the right watering system depends on the size of the wall, the water supply and the substrate system that is used. Checking the system once a month is advisory.

Large green wall in Hendrik Ido Ambacht.

Looking after plants in a green wall

Actual plants need additional maintenance, besides watering. Adding fertilizer, trimming, periodical renovation and preventive and curative care also need to be taken care of. Maintenance is essential to keep the green wall in perfect condition for a long time. Depending on the type and the size of the wall, this needs to be done from four to twelve times per year.

Sometimes people think, “Let nature go its course; the greener the wall, the better” or “we can manage giving a little bit of water and if we do it ourselves, it will save money.” Of course, this could work for a couple of months, but the consequences become apparent soon. The plants in the wall tend to overgrow each other. Regular pruning is needed for a balanced growth, ensuring the plants will keep for a long period. Timely and professional monitoring and treating pests and plagues is also important. This will keep a check on the costs.

Maintenance using scaffolding

Taking care of a high green wall

Green walls measuring three metres in height can be taken care of with a ladder. For higher walls you will need scaffolding or a cherry picker. With leaning walls or other walls where you can’t use both, mountain-climbing gear could be the ideal means for tending to the plants. There are even green wall systems that include a rail and a gondola hanging from it. Please note that these should to be used only by well-trained and experienced maintenance professionals.

If a higher green wall is designed for a building, you will need to look into its suitability. Ask yourself the following questions when considering the installation of a large-scale green wall:

• Is there sufficient light?
• Is there enough space underneath the wall to install a scaffolding or hydraulic gear for maintenance?
• Is there enough room above the green wall for the construction of to fasten climbing gear?

Maintenance at great heights

In short: make sure to involve an interior horticulturalist in the process as early as possible. This should be someone who is specialised in constructing and taking care of green walls. He or she can also advise on the total costs, including the up-keep, and is clear about the guarantees.

This ensures your green wall will remain a spectacle for a long time.

If you put this question to various professionals, who are all into green building and interiors, you will drown in their advice! During the lectures at the Buildin’ Green conference, but also during the workshops and in the corridors, various inspiring ideas and experiences were shared. An overview:

Know and convince your client

“Do we know the questions, problems and pain of the client?” one of the participants wondered. Investigate the real issues and focus on solving these, is her advice. “Focus on projects that have been realized and seduce the clients with numbers and results,” another brought forth. The biggest ‘but’ is often maintenance. “Why do our clients never complain about the window cleaner, but always about the maintenance of the plants?” workshop instructor Marieke Karssen wondered. It seems the need for control is at the root of this problem; because plants can get sick, as we know. A service contract specifying an obligation to achieve a result can be a solution as it can take away the client’s worries.

Selling to other industries

Who is already selling plants to shopping centres? Because green sells best to offices, but also to shopping centres, factories, the hotel and catering industry, health care and indoor swimming centres. So, start thinking about other industries. “Look for the bare walls to lead you to new business,” says Mike Weinmaster with a smile.

Green wall Restaurant Fortuijn Haarlem

Outstanding example

Outstanding green walls can even bring you new clients. “We have seen a tremendous growth in the last couple of years, while we have been working on green walls for ten years now,” says a green entrepreneur who operates internationally. Councilman John Nederstigt of Haarlemmermeer adds: “What we need are concepts that can be implemented simply as well as solutions for existing buildings.” Wendy Dieben is a project leader at the engineering office of Haarlemmermeer and involved in the projects ‘Green in the classroom’ and ‘Green stepping stone’. “With these two projects we want to make our schools more sustainable. We have involved the children in learning more about the effect of plants and nature and so enlarge their feeling for green… The positive effects of green on the indoor climate have been proven scientifically. That is stimulating. My view is that you need to demand more green when you develop social property. We need outstanding examples. Civil servants can stimulate people to treat green differently.”

Health and ergonomics

Take people’s need for wellbeing as your starting point, is what Owen Zachariasse and Djelko van Es will tell you. Don’t just convince the facility manager, but the boardroom as well, and talk with the HR department, because it is a health issue, says architect Daan Bruggink. The pull from the employee and consumer to put green building on the agenda is also important. Working both top-down and bottom-up appears to be the best recipe. “Consultancy agencies that are leading in ‘Het Nieuwe Werken’ (‘the new working’) don’t necessarily think green,’ observes Djelko van Es. “’Het Nieuwe Werken’ wasn’t invented to stimulate the worker’s wellbeing, so there is a niche if you want one.” “The office furniture business influences both ergonomics and health, where interior horticulturalists don’t, but plants are beneficiary for with good working conditions,” adds Robert van Aerts. He pleads for a more active lobbying of the sector.

Various factors influence the wellbeing in the workplace. Source: Djelko van Es

Showing a profit

‘Clients don’t want to invest in it’, is an often-heard complaint of green builders and interior landscapers. The audience has several solutions for this problem. Make it clear that people need green to improve their productivity. Think in numbers and profit, show the results and add an obligation to produce a result in your contracts. Make note of government funding in your quotations and tenders, but subtract them of the total amount to seduce the client.

Green is doing better at home

How do we make consumers more passionate about green? Strangely enough consumers are already enthusiastic at the moment; especially when it comes to health. But how do get this trend to the work floor and to more consumer groups? One solution is to involve young people, and let children get used to green as good, healthy and normal. And make sure green walls become cheaper. Buying a green wall at the garden centre? Why not!

Multi-disciplinary collaboration

With so many professionals from various disciplines put together, it quickly becomes clear that collaboration in green is rewarding. “Start collaborating outside your own business sector,” says Djelko van Es. “Why not work together with air conditioning fitters? If plants can improve the air quality, then they will aid these fitters to enrich their product. Think and/and instead of or/or. Raimond de Hullu adds that you need to collaborate in order to be visible. Another participant says: “You need to get the architects on your side, they can influence the client.” Some architects are not entirely sure. They confirm that the client is the central person. “The architect needs to listen whether the client thinks green; this is an area where mistakes can happen.” Peter Goossens is a researcher at the Research station for ornamental planting in Belgium: “My research on green wall systems bridges a gap between interior horticulturalist, architect and client.”

Information centre needed for innovation

Project developers want to build green, but view plants more like decoration than as a profitable part of their project. Sharing information will speed up any process. Sharing information is a precondition for growth and innovation. Green building should also get a place in the polytechnic schools. Daan Bruggink: ” Students already know what is sustainability and think about the eco society, but they know little of natural systems.”

The government’s role

Buildin’Green took place in Park 20|20, in Haarlemmermeer. This is an area adjacent to the Schiphol and the “Groene Hart”, the green lung (or rather: heart) of the western part of the Netherlands. Here city councils, provincial administrations and partners in civil society look for durable solutions for new development and renovations and also make their inhabitants more conscious of the value of planting.

Councilman John Nederstigt of Haarlemmermeer, responsible for sustainable economic development, innovation and education, has made an effort, since he took office in 2010, to make the local economy more sustainable and create a better working and living environment. But there are also responsibilities as well as opportunities to tackle climate changes at a local level. For Haarlemmermeer this means more green spaces, to achieve more balance in an area with rather large carbon dioxide emissions. Park 20|20 is an inspiring example and Schiphol is on its way to become greener too. Smaller projects also give local governance a chance to influence, as the green walls in fifteen schools in this area will demonstrate. “The best way to convince people that green works is letting them experience it. Test results on paper don’t work.”

Park 20I20

Province unites

Karin van Hoof is policy advisor with the province of Noord-Holland. “The province plays an initiating, informative, observing and uniting role for building green but also in planning green. For Noord-Holland I am involved with ‘Groen Kapitaal’ (Green Capital), with which we want to improve biodiversity outside nature reserves and enhance the knowledge of the social and economic value of green. The province is still finding its place and duty in this policy area. We are starting up Information cafés to get in touch with representatives of other segments. And in the area of sustainable building we try to set an example: our provincial government building just saw a sustainable renovation, changing the energy label from G to A+ with a green roof and, more recently, the durable the archaeological depot in the province in Castricum, called ‘Huis van Hilde’ (House of Hilda).”

International approach

Rob Franken of Van der Tol Landscapers underlines the importance of the diversity of attendants: “It is a welcome surprise to see so many disciplines gathered here. All participants are interested and have put this matter on their agendas. This is a good sign! The employer’s organization needs to propagate green building on a macro-economical scale; that’s more effective than convincing people individually.” The Swiss landscape architect Gerhard Zemp was interested in meeting other participants and learning new things. ‘In Switzerland there is no professional association for interior horticulturalists and yet we all face the same challenges. We should all work to influence the market and inform the public.” Former EILO president Robert van Aerts wants to look at green from a European level. “If we want to put interior planting on the agendas as contributing to a healthy workplace and good working conditions, we must increase our lobbying in Brussels. The office furniture industry has already succeeded there. It there is too little attention for interior planting, this is mainly due to a lack of communication.”

As an interior landscaper, what trends can you best respond to in this rapidly changing world and ditto market to make your business really flourish? Dutch VHG Vakgroep Interieurbeplanters, the union branch for interior landscapers, organised a gathering to discuss trend watching. The appropriately chosen venue was ASR head office in Utrecht where, with a view to the future, they had decided to concentrate all 1300 employees in a single office building, with different types of workplace, indoor, outdoor and roof gardens, as well as recently developed large green façades. This 70,000 m2, one of the largest office buildings in the Netherlands, underwent major refurbishment, has been nominated as one of the 10 best in the country, and is also BREAAM certified.

‘One thing is absolutely certain, nature is always right’

Trend watcher Aafje Nijman used this thought-provoking quote from architect Thomas Rau to set the tone for an exciting exploration of several major developments around the world and the trends that could be derived from these developments for the green sector. A significant conclusion being: even though social and technological innovation sometimes develop more quickly than our human adaptability, every entrepreneur should learn to look ahead and to draw inspiration from developments outside their own sector. Only then will you be able to respond quickly. And respond you must, because consumers switch quickly too. While the broad concept of ‘sustainability’ has become a little worn, ‘nature’ will play an important role. In many fields, big data analysis tools will render specialised knowledge largely superfluous, and new interpretations of the concept ‘gender’ will lead to office design becoming more feminine. Flexible working relationships and cutbacks have also led to a significant reduction in the number of physical offices and consequently to far fewer related projects for interior landscapers. Nijman observes that wherever you look, plants are ‘hotter than ever’; numerous restaurants and shops are ‘going green’, visit the Woonbeurs home interior show and you have to wade your way through plants and at the design fair in Milan the jungle of plants practically concealed the furniture on display. They were even filming nature commercials there.

Experience is gaining in significance. Marketing the experiential value of plants, to the extent that plants become a natural element of interior design, is therefore key.

Radical ReFrame

Every year, Nijman writes an article in which she translates trends into changing consumer values, and style changes into interior design. While recent years were dominated by economic recovery she predicts that 2017 will be one of radical reorientation. Events in the world around us have an ever greater impact: wars, refugee flows, climate change, radicalization. Former frameworks are no longer effective and it is very uncertain ‘where everything is headed’. Uncertainty can breed fear but it can also breed innovation. This is reflected in four value orientations:

Dis-close; in search of the truth

In this rapidly changing world, people seek stability and seem to find that mostly in nature and in themselves. Our own inner compass and senses are increasingly key to us finding our way through the complex reality. Nature is practically placed on a pedestal, also as a refuge or retreat, a place of healing. In interior design, this is reflected in green areas you can crawl into, curl up and calm down. Let nature tell its own story.

Off-base; looking for balance

The human dimension is again key; a smaller scale to help us grasp complex things happening on a larger scale. Design and furnishing change accordingly. Small plants are gaining in popularity, sometimes even replacing other products, e.g. using plants to create a curtain at the window.

Gain-change; new rules

The economy is recovering and the energy is practically tangible. New business models and products are being developed. Green products are associated with energy and strength. Plants as suppliers of oxygen. People don’t necessarily have to own the plants themselves. Lease and loan constructions are quite feasible, for instance.

R-Evolution: limitless possibilities

Technology is evolving rapidly. Devices are becoming increasingly ‘human’. The boundaries between people and plants will eventually fade. Apps enable us to communicate with plants: smart gadgets tell us when they need feeding or watering, or whether our indoor environment is an ideal temperature or humidity. With the aid of technology plants can become energy suppliers, or provide light. Plants will play an increasingly important part in such new dimensions as sustainability, in building construction and the development of ecosystems.

Trends in facility management

René Wentink of Facility Management Nederland explored the trends in the facility sector that are relevant for interior landscapers. For any organisation it is essential that housing, service and resources contribute to the objectives of the organisation as a whole. These objectives are continuously reviewed against changes in society and among customers. One important trend is ‘Lean Management’: doing more with less. Saving costs and reducing the number of square metres are fundamental. There is also an increasing drive towards Social Enterprise. Businesses and organisations seek to create value. The role of technology and data analyses will become more and more important. Comprehensive contracts will become more commonplace, effected with consortia who handle practically the entire process themselves i.e. also supplying all the staff throughout. So someone could well be working at reception in the morning and caring for all the plants in the building in the afternoon. We see a decline in external hiring of specialised knowledge.

Interior landscapers should consequently ensure they are involved in the process from a very early stage. They can no longer afford to wait until the new building has been completed to get involved. Involved not just as plant supplier but as a partner, an experience creator. They should become an additional link in the chain. This could be by providing test arrangements in buildings, for example, offering special deals for staff, creating a seamless inside-outside transition, and supplying new products that help generate the image a company wants to project. Identify and act on trends, such as ‘edible’, for example. Why not create a green wall using herbs and vegetables, which could then be used in the staff restaurant thus avoiding transport costs. That would contribute to the company’s sustainable image as well as its story. More than the actual plants, let that be your unique selling point. Experience is becoming a priority. Yet, all too often in the business world the health effects of plants are still overlooked. A company’s HR manager is actually more important than its facility management department, in that respect. So focus on them.

Plants on a cruiseship. Photo: Ambius

Wentink can be inspired by entrepreneurs who build a clear and recognisable profile for themselves by only working with second-hand plants, for example, or by an area such as the Zuidas business district, which is rapidly developing into a sustainable prime location. Networking is becoming increasingly important, so make sure to always present yourself and your business at events in such locations, e.g. events held by “Hello Zuidas” the organization dedicated to managing the Zuidas area. For large projects, particularly focus on the architect as he/she will be involved in the earliest stages of the process.

Embrace new markets; look at the enormous Harmony of the Seas cruise ship, which recently attracted much public interest in Rotterdam. It has some 10,000 plants and 50 trees on it. Sailing promotion for the Dutch green industry.

Company doctors of the future

There are plenty of business opportunities in the green industry! You can turn market uncertainties into opportunities. That’s to say: you can if you can convey the experiential value of plants, act on technological innovations and modify your products accordingly, are able to develop new revenue models, and have relevant knowledge of the positive effects of green. That would enable you to advise businesses and organisations on a healthy interior and pleasant working environment, offering them products tailored to their specific situation. You’d be more than a supplier or maintenance technician. Interior landscapers as the company doctors of the future…

Most interior horticulturalists will have encountered this phenomenon in recent years: clients had to cut costs on those things that are considered a luxury. Most often the plants at the office are the first to be victimized. Besides, a working area without plants is more quiet and functional as is asserted by the ‘lean’ thinkers, thus killing two flies in one swat. The idea being that, in a world where people lose their jobs, it’s not done to invest in plants and other non-functional extras.

No matter how wide-spread this conviction is at the moment, there is very little scientific proof to back it. On the contrary, it was the opposite that was demonstrated (Haslam & Knight 2006): plants do increase the concentration and productivity of workers and are in fact a sound investment. This means it’s high time for a study investigating whether ‘lean’ really improves quiet concentration, or whether it’s the other way around and it might not be so clever after all – even if it seems to be such a smart way to cut costs.

 Does lean mean more or is it the other way around?

Four scientists from three British universities and one Dutch university have investigated three fairly large field studies in this area  to see if this is true: does lean mean more? Or is it the other way around: can people concentrate better, are they happier with their workplace and more productive if there are plants in the office?

 In what ways do plants work their wonders on the work floor?

Generally speaking, several studies in the past years have turned up three significant reasons:

1. 1. Plants clean the air: not only do they produce oxygen, they also reduce particulate concentrations;2
   2. Plants are alive. Even at a subconscious level we are aware of this and in a biological sense we feel safer in natural surroundings. Patients even heal quicker and are calmer when they are surrounded by plants;
   3. When plants are introduced on the work floor it implies the manager or organization take good care of the workforce and that improves the co-workers’ sense of wellbeing. This last result, however, can also be achieved by adding art works to the workplace. This makes it a difficult factor to measure in the three studies mentioned below. The ‘lean’ space is an area where nothing happens and where, psychologically speaking, the boss is not really looking after his employees. It is recommended to arrange for some sort of enrichment in the ‘lean’ areas, in order to correct this factor.

Experiment 1: The green and not so green areas of the ‘office garden’ of a consultancy firm

The final factor mentioned above – the boss looking after the employee – certainly played a role in the first experiment. This took place in a fairly large office (4,875 m²) of an international consultancy firm in London. It was housed in a large open-plan office with some adjoining smaller meeting rooms. Half of the large office area was decorated with plants and the other half was kept ‘lean’.

The employees were asked questions twice: eight weeks before the arrival of the plants (T1) and three weeks after they were put in place (T2). Each time about 60% of the employees participated in the questionnaire, unfortunately the overlap of both groups was small: only 30% of them filled out both questionnaires. In absolute numbers they were 67 people. And whether they worked in the lean or the green office area: in terms of age or function they were similar.

The people in the green area scored better with respect to concentration and productivity. But, strikingly so and possibly because it was one large office space, both groups scored better in the second questionnaire, on all points, the green group scoring even better than the lean group.

 Experiment 2: lean and green call centre floor at an insurer

The results in the graph above, indicating that employees of both halves of the open-space office felt better, was not seen in this second experiment. Here, two identical call centre teams were compared, each located on their own office floor, measuring 360 m2, in the same building. 75% of the employees answered the questionnaire at the start of the project (T1). 70% of the respondents participated in the questionnaire two weeks after the plants were put in place (T2) and 3.5 months later, still 58% of the employees participated. And in this case as well, a large number of the questionnaires couldn’t be used because they didn’t join in all three times. In terms of age, sex and work experience, the groups could be compared well.

However, another issue did arise. For the employer a productive helpdesk employee is a fast-working helpdesk employee. And this type of productivity did not increase noticeably by the plants. Apparently it also has nothing to do with concentration, because this did rise significantly. The most striking positive aspect is the worker’s satisfaction with the workplace. This really improved after the introduction of plants in the workplace and remained on top even after 3.5 months. This can be explained by the relatively dull job of these workers. Apparently plants do make a difference in the satisfaction with the workplace if this is the case.

Experiment 3: measuring productivity

For the third experiment a consultancy firm was used again. Here the question was if an office space filled with plants would lead directly to an increase in concentration and productivity. Two-thirds of the staff joined in the experiment, with 16 male and 17 female respondents, aged 22 to 33 years. These were put into two identical rooms, safe for the presence of plants of course. The workers were asked to execute two tests. One in which they had to answer difficult questions and one where they had to select and process a lot of information in a short time. Both tests took stock of the speed and accuracy of the employees. Half the respondents did the tests looking at three plants, at least; the other half did not have this view.

The results are quite clear: in the area with the plants present both tests were finished quicker and with fewer errors. This corresponds with research that was carried out in the past. Please note: for the first time ‘green’ has shorter lines in this graph, but this is a correct representation: less does mean more in this graph.

 The conclusions

The first two studies could demonstrate the effect of plants on the experience of the workplace well, and that this increases on all levels. The third experiment showed that concentration and productivity will rise significantly if there are plants in the office. All these results correspond with earlier research.

The ‘the boss looks after me’ factor deserves more in-depth observation in follow-up studies of the ‘lean’ office. This will heighten the participation of the respondents in this group especially and will make follow-up results more reliable.

Based on these studies one could come to the conclusion that plants do benefit the workers as well as their output. Putting plants in the office is a sound investment with actual financial returns for an organization. Also, we can see there is no proof for the domineering zeitgeist and present-day managerial claims. The contrary is true: green clearly wins!

After the last very succesful EILO trips to Scandinavia and the Netherlands, this year we will go to the UK. The programme will be revealed soon, but we can already promiss you it will be interesting! Apart from visiting a number of inspiring interior landscaping projects we will present a special EILO publication ‘Plants XL’.

The excursion will take place on September 20-22. Please save this date!

One of the conundrums behind the message Into Green conveys, that plants make people healthier and happier, is the question how plants purify the air. The fact that plants filter Volatile Organic Compounds (VOCs) such as Formaldehyde or Benzene from the air was first demonstrated in the nineteen-eighties, when W.C. Wolverton published a high-profile study on the subject. Performing a study for NASA, he researched how good air quality could be maintained inside a space capsule, even for a whole year, and discovered that plants could contribute to that significantly thanks to their ability to break down all kinds of chemical compounds. Besides substances we exhale, these also include substances released from building materials and plastics, for example. And all the plants required in return was water and light. They didn’t get used up nor blocked or contaminated which, given the situation, was highly efficient. He continued to research the phenomenon, and even published a book with the top 25. Job done, you would think: study performed, these are the top 25, these are the plants we should grow in our homes and offices. However, the inclination to jump to conclusions and compile Top 10 lists too readily can hinder good research for years. Because plants are living things and naturally grow very differently in real life compared to a test environment. Stress in plants, due to inadequate light or water, for example, is immediately reflected in their performance. There are also numerous varieties within the different species and the more research we conducted, the more complex it all became. The ability of plants to break down harmful substances was also shown to vary significantly from one substance to another, so when is air completely ‘purified’? And despite all these revelations, that one key question remained unanswered: how do they do that?

First create order

High time for an orderly new test by someone who has more than earned their spurs researching air quality in greenhouses. In the context of the top sector programme De Groene Agenda (The Green Agenda),  Dr. Pieter de Visser was commissioned to create some order in the 30-40 years of research since Wolverton. He first read up on the existing research before testing for himself whether the various claims were reproducible. We paid him a visit.

The role of water

There was one area in which he was soon able to make a firm point. Despite the fact that different studies sometimes contradict one another, as indeed they should in science, in his research design he was equally able to demonstrate how plants are particularly able to absorb Formaldehyde through their leaves. This absorption behaviour, as well as the breakdown into harmless compounds substantiated by the literature review, is probably reproducible for all water soluble pollutants such as Ammonia and Sulphur Dioxide. These substances are absorbed through the stomata of plants and into the plant’s ‘ordinary’ photosynthesis/ decomposition process and aids the production of sugar and oxygen, provided the concentrations are not too high. The test in which he compared the reduction of Formaldehyde in the air by plants with the reduction that occurs when only water is introduced was particularly interesting. The reduction was practically the same in both cases. However, as Pieter points out, plants do something with the substances they absorb, turning them into sugar or oxygen, which water does not do. So to remove the Formaldehyde from a space altogether, you would have to replace the water continuously. So water does bond but does not convert the substance.

The route of substances that bind to fat

But, Peter soon wondered, what part do plants play in breaking down fat soluble or lipophilic VOCs such as Xylene or the extremely hazardous Benzene? This had been poorly researched until now and it emerges from both literature studies and his own practical research that the absorption and possible breakdown of these substances occur in a different place altogether. Not in the leaves, in fact they are hardly absorbed or broken down by the plant at all, but primarily by bacteria and fungi. These live partly on and near the leaves but mostly around the plants’ roots. Where the plant and soil life meet, sugar (from the plant) is constantly exchanged for all kinds of substances that the plant needs from the soil and which fungi provide in abundance. During that process, the VOCs are included as food source. Or, as Pieter put it: ‘Thanks to their huge gene pool, microorganisms have so many enzymes available that they adapt very easily and then break down whatever is present.’ The prospect of compiling a definitive top 10 any time soon, became even less likely, but Pieter continued his research. ‘While the plant did reduce the level of Xylene in the air (= ‘depletion’ in the graph below), we discovered that the xylene that attached to the plant and the test equipment were later released back to the air. This so-called re-emission is an effect of the chemical balance with the surrounding air and I would very much like to research this further. Because while xylene levels certainly are reduced by plant absorption, this stops at a certain point, when the balance has been reached, and we want that reduction to continue.’

The test apparatus is a breakthrough

 One of the biggest hurdles at the beginning of this research was the question: how can you test how plants (or the microorganisms living with them) do what they do? The existing test apparatus at WUR only enabled researchers to blow air at plants and watch how the plant reacted in terms of growth or flowering: fewer leaves, fewer fruits, less growth. However, the commissioner of this study also wanted to know what happens to the substance. Pieter goes as far as to claim that his team is the first research group to devise a set up that can measure not only the air but also the water and the soil. So you can see exactly what is left in the air and what disappears into the plant and the soil. Dr. Pieter Visser, WUR/Alterra

Where do we go from here?

He explains that this study is really only just beginning. This broad research can and must now be narrowed down to a specific area of focus. What effect do poor light and water conditions have? Or what part does the pot play? What happens to the VOCs that bind to fat if you accelerate the supply of air. He also wants to learn more about the role of time and the tendency that plants and their microorganisms apparently have to achieve a chemical balance, and how they actually work together. This is all very difficult to research and before you find the answers, you gain other, unanticipated insights revealing realities that are even more complex and fascinating than you had ever imagined. But then, that is the beauty of science. We will follow developments with interest.

Author: Koen Aartsen

From nature to office-like indoor spaces

People influence their environment, often to benefit their own well-being*. This includes such things as food production, central heating and lighting. Animals ‘cultivate’ their environment for similar reasons; ants build huge underground strongholds, beavers create whole river delta’s and elephants keep the savannah clear of trees. Generally, the environment determines the degree to which needs can be met and closely examining the natural environment of the animal or, in this case, the people in question would enable you to define the appropriate (or better) circumstances for proper development and to maintain or improve the level of well-being. This happens increasingly in zoos. And in towns and cities, where more and more people live; some 75% of the population in Europe. People who also spend around 80% of their time indoors. This makes it worthwhile to explore ways of designing the indoor environment in a way that suits our ‘biological organisation’ and stimulates our brain in various ways. Offices are particularly interesting in this respect; spaces where people spend a lot of time and which influenced them but which they themselves have relatively little influence on. In this context, there is growing interest in and an ever wider range of plants for office landscapes. It appears that people thrive in as natural an environment as possible which, in turn, benefits the organisation.

 SC Johnson headquarters: office landscape with natural daylight, designed by Frank Lloyd Wright, built in 1936

But how does it work? Science has been seeking to answer that question since the eighties, particularly from a psychological angle. This has resulted in various theories explaining the restorative effect of nature: The Biophilia Account, Attention Restoration Theory, and Stress Reduction Theory. These theories focus respectively on an innate need to interact with nature, and psychological aspects that are important to our day-to-day functioning, especially attention and stress. Interesting studies have been performed to measure this and have often revealed that the presence of plants, views of nature or even just images of nature can help reduce stress and/or increase attention levels. The mechanism that causes this effect remains intangible, however. So perhaps we should try to explain it from a different angle.

Fractal patterns: The visual basis of natural shapes

People have a strong preference for visual stimulation. So there must be something about the shape and configuration of plants that the eyes convert to a signal which, once transmitted to the brain, has an effect on attention and stress. If that is the case, you would expect the effect to be the result of an innate brain configuration that develops with the appropriate stimulation.

An interesting study recently researched this visual pathway. The theory that describes this mechanism is called Processing Fluency, which states that some shapes and patterns are easier to process than others and that this processing simultaneously affects how you feel (the so-called affective effect of an object). In nature, shapes are often made up of recursive patterns, known in mathematics as fractal patterns. Mathematical fractal patterns can recur infinitely. A fine example of this is the Koch curve, see figure 2. Patterns in this category are called statistical fractals.

Koch curve, example of a statistical fractal.

Nature applies similar iteration, albeit with a degree of randomness as a result of which iteration does occur but with slight variations each time. These patterns are called exact fractals, natural examples of which include clouds, ferns and coastlines (see figure 3). Applying this mathematical approach to natural patterns makes it possible to identify the properties of an image precisely and to generate new images on the basis of those properties. The properties which determine the degree of iteration (i.e. complexity) and the randomness of the fractals are the parameters D and P.

Examples of fractals in nature. Left, a layer of clouds; centre, the mathematical creation of a fern leaf; and right, a mathematically generated coastline.

Imagine a blank square. If an unbroken curved line were drawn in that square the D value would be 1, indicating that it contains no fractal structure. The maximum D value is 2, in which case the whole square would be black and also contain no fractal structure. Between values 1 and 2, the line may curve repeatedly, as it were. The repetitive pattern of a fractal line will cause the line to take up more and more space. The higher the D value the finer the line structure. Figure 4 shows how, from left to right, more and more curves occur in the line and the D value increases.

Example of how a fractal pattern changes in terms of naturalness and complexity with the changing P and D values.

The P value determines the percentage of curves pointing ‘down’, thus generating a more random, ‘natural’ shape. Figure 4 shows several Koch curves with varying levels of complexity. As could be seen before, the pattern repeats itself by adding a triangle at set points. The P value determines the percentage of these triangles that point downwards, which ultimately result in the curves looking more like a natural coastline, while a P value of 0 generates a more Oriental pattern.

How fractal patterns can explain the restorative effect of nature

This approach makes it possible to create images varying in complexity and naturalness. It can be applied in research to display different variations of such images on a screen and subsequently perform measurements relating to preferences, mental effort, attention and stress, for example. Without going into the exact methodology, eye-tracking, electroencephalography (EEG), and skin-conductance can be performed to examine how our eyes view a particular image (eye-tracking), the corresponding changes in brain activity (EEG), and any effects on the stress level in our body (skin-conductance).

Interesting findings have emerged from these studies, such as the fact that people prefer images with a D value of approx. 1.4. The D values of natural patterns are roughly between 1.1 and 1.9, and those most familiar to us, such as clouds, trees and mountain ridges, are between 1.3 and 1.5. This implies that our visual system is adjusted to the shapes we see most often, in nature anyway.

It also emerges that looking at images with this preferred complexity can reduce stress levels if stressful mental tasks are performed while looking at them. That is to say: researching the relationship between visual processing and the physiological effect of that process could help us in our search to define the restorative effect of nature. And in discovering effective uses, in offices for example.

Enhancing the office landscape with fractal stimulation

The idea that our visual system has become specialised in processing natural patterns sounds plausible. Manipulating fractal patterns makes it is possible to link physiological and psychological measurements. This could enable us to explain the restorative effect of plants, for example, less speculatively than the current psychological theories. If our visual system can easily process fractal patterns, such as plants, then that indicates that we can easily distinguish between fractal patterns of varying complexity. That is what enables you to spot a predator or prey among foliage or undergrowth, by its recognisable patterns, such as a tiger’s stripes. Being able to quickly distinguish between the ferns and figs and a tiger, could prove invaluable.

To return from this imaginary jungle to the office landscape: if visual stimulation in the form of plants does indeed make processing easier, then staff would have more ‘inner space’ and be better able to concentrate  on other tasks. Even stress reduction can be linked to visual processing of nature. It makes working all the more pleasant.

Indoor plants can enhance our brain activity. That is good news for companies looking for effective ways of improving staff well-being and productivity. Gazing out of the window while you’re working might not be such a bad idea after all, provided you take in the fractal patterns that is.

* Well-being is a much-used term but there is little consensus on the precise definition. The Oxford Dictionary defines well-being as: “the state of being comfortable, healthy, or happy”, and this is used in this article. As this encompasses health, “well-being” is a very broad term