Landscapes are all about creating micro-climate, or would be, if designed for that goal. Why is this important and what do I mean?
Almost all life is contained in a thin crust of soil, a wedge of atmospheric gases, and water. Plants are the principal medium that interacts with and regulates all three. Absolutely nothing else does this as well, or at all; think about it.
The way we organise our plants in our urban landscape will determine how well this interaction occurs, how successful it is. Yet I have never heard of a single project that has been developed with this understanding and this goal in mind. With climate change, we urgently need to re-think the way we design our landscapes, and why we design them. Whilst all the human-centric design reasons will always hold true, we need to layer into our thinking this new understanding of how plants interact. To build new ecologies, new ecosystems, we have to design for plants to actually function, rather than just look nice. For when they do this, our environment literally comes alive. More importantly, they might just, if done on sufficient scale, save us from ourselves.
When I use the word treescapes, I don’t just mean trees and grass; we’ve had that for years in the form of parks, and in their traditional form, they’ve done little for us. No, our designs need to build up layers of living material – biomass, for with biomass comes moisture entrapment, shade, food for insects, etc. Think of it in terms of height and depth of microclimate. How much depth is there in a stretch of irrigated grass, maybe 50mm above ground, 200mm below? No species variation, so what we have is little more than a green desert, albeit one that can hold bit a of moisture.
Trees in paved streets are also less able to generate micro-climate, but they are a bit of an exception, as they provide shade for people to walk under. Where width allows, even here we should layer our planting.
If we replace that grass with a range of groundcover plants – not a monoculture – you begin to get a little more variation; different root structures and depth, different foliage shapes, height, form and flower. More variety, more microclimate, more food source, more ecology. Looks good too.
Next we add shrubs and suddenly we are into an new realm, that of woody plants (I’m being simplistic here, many groundcovers are of course woody). Shrubs create three-dimensional space with their frameworks, within which micro-worlds reside. Deciduous plants shed their leaves, as do evergreens, and this begins to build leaf litter – mulch. Don’t tidy it up! We need ecologies in that soil, and microbes need food. Our obsession with tidyness has a lot to answer for. Suddenly, we have height in our micro-climate, three-dimensional form. We humans (for we scale everything according to our own height and perception) can walk amongst these plants, take part, interact. Our microclimate is now two metres high, maybe more. But something is missing and it’s still too hot…
Trees! Now we have a game changer and our micro-environment just became vast, in relative terms, maybe up to 30 metres, though 10-20m may be more average. We now have true diversity of shape, height, leaf, flower and roots. We have shade! Under trees it may be 10°C cooler and we love it. Plants love it too. Moisture now gets retained within the human habitable zone, fungi and microbes thrive in soils, insects and birds abound. This is our urban jungle and we need it. The planet needs it. This tiny sliver of crust we live on can be rich, abundant, in every climate and every place, if we put our minds to it, if we have the will. And when the planet becomes searing, creating livable environments with trees of any type, may be the only thing that keeps us alive, unless we become troglodytes.
This is the next level of landscape design, the new challenge; creating future ecologies and environments that matter, that keep us cool, that give us resources and soothe our souls. We will create new (novel) ecologies that fit the changing environment, trans-migrating parts of ecologies that once lived elswhere. In that place they may be dying out, as might your local ecology. If they now fit where you live, that’s where they need to be. In turn, that place of origin may itself need to adapt and change. In all things and all places, we need microclimate, shade and soil.
Almost all urban landscapes are contrived and designed, due to their artificial nature and short timescales of development and use. We see increasing use of mature rootballed trees and extensive hard landscape and this is normal for intense inner urban areas; I do get concerned that the increasing complexity of urban planting systems divorce trees particularly from their natural functions and prevent the occurrence of the biological interactions/communities that go to make up an ecosystem. For example, I have seen trees planted whose surface levels are around a metre below the surrounding paving level. No matter how well designed, this seems fundamentally wrong to me.
So I’m thinking that there must be a way of dealing with the majority of less intense landscape zones (especially where there isn’t the financial budget that a high-end development attracts) to provide urban regeneration, ecological restoration and biophilic connection, all on a modest budget. This would create a new method to allow for wide-spread adoption in urban and suburban zones. I think the solution comes from Nature’s own process of natural regeneration and a developed philosophy of minimal (but specific) preparation.
silver birch are pioneering species for natural regeneration
Starting from the observation that Nature is very efficient at regenerating itself, what can we do? Too often, I have seen unnecessary interference in this process. I still recall that a few years after the great storm of 1987, I walked through some nearby National Trust woodland of pines and birch. A great deal of damage had been done with many trees blown over. Birch had however, regrown abundantly from dormant seed and was already three or four foot tall. The NT then sent in the bulldozers to clear out the fallen wood so the area could be – replanted. I watched them tracking over all the natural regeneration. Why didn’t they just leave well alone? The restoration of the woodland was only slowed down by such clumsy interference and this was not even a productive forest.
If we simply broke up paving in our urban centres and loosened up the sub-base, what would happen? Nature would soon find a footing and things would start to grow; however, that process would be too slow and unpredictable for human sensibilities. So what if we did a little more, adding a small amount of topsoil to the rubble, planting small (1+1 year transplants) bare root trees and shrubs, with plugs of understory forbs, ferns and grasses. Starting so young, we’d generate a successful community in no time. These could be designed as narrow ribbons – two to four metres wide, inserted into suitable wider areas of paving.
An urban area suitable for natural regeneration
The above area was one I thought would be suitable for such an approach; there are many such areas throughout all urban spaces. They cry out for regeneration, yet seldom can this be done for lack of adequate finance. Below is a quick sketch showing how it might look.
Sketch showing regenerative planting
The benefits of such an approach would be huge. It would cost far less than using a traditional approach to landscaping such an area, maybe half (I haven’t costed it!). The care would move from maintenance to management, using a rotational coppice methodology, rather than trim and tidy (which always ruins a plants natural habit. Biodiversity would be hugely enhanced, air pollution mitigation would increase, wind buffering, urban heat island reduction, stormwater runoff (they would act as rain gardens) and of course, our biophilic needs, our connection to nature.
We are now a decade into the explosion of living or green walls. There have been many successes and some notable failures along the way, some of of which may be system-induced and some caused by inadequate or inappropriate maintenance regimes. Assuming we now have systems that work at least reasonably well, what is required by way of maintenance to keep walls looking good?
First of all, we have to acknowledge it is the large, commercial projects which get the attention and sit within the public eye. If anything goes wrong with these, it is noticed, big time. Commercial walls, I have found, are governed by financial pressures and that can sometimes mean that over time, budgets are cut and maintenance regimes compromised. When maintenance goes out to commercial tender, it is usually the cheapest price that wins.
Secondly, we have to understand that there is a profound difference in the way we perceive vertical landscapes from horizontal ones. With ordinary planting beds, we would plant probably between five and nine groundcover plants per m². Living walls are planted at between 30 and 100 plants per m², a highly artificial and crowded environment. Yes, we are treating these as groundcover which knits together, but unlike horizontal beds, gaps between plants are not deemed acceptable. It is also harder for plants to spread or fill in laterally, depending upon the system they are planted into. Visually, when you look at a living wall, you look straight on at eye-level, then upwards. So the lower sections of walls can come under intense scrutiny. Any failures have to be replaced and the rate is higher than that of horizontal planting, for the aesthetic reasons just stated.
Thirdly, living walls depend upon the right plants being chosen; they have to have the right characteristics of habit, growth and longevity. Some common garden plants are notoriously temperamental, short-lived or subject to pests such as the notorious Vine Weevil (which seems to attack an ever-increasing variety of plants). As a designer, I have previously used many plants that I don’t use now, and I find the list is shrinking, as you learn about a plant’s ruggedness over time. We are still pioneering a new methodology and now I’d rather use a smaller palette and feel more confident about it’s long-term success.
Fourthly, finally and perhaps of greatest importance, is the maintenance given to a living wall. I prefer the term living wall to green wall, because it reminds us that they are just that, living. They are also put into an extremely hostile and unnatural location and aspect. Sometimes those who look after them don’t do a good enough job. Many commercial landscapers are not horticulturalists and don’t really know that much about plants. That may sound shocking (and I’m pointing fingers at no-one, for this is just they way things are) but a Kew or RHS trained gardener is unlikely to be employed in a commercial company. Even knowing what to do for the best health of a plant on the ground could be inappropriate if done to the same plant on the vertical.
The pics above show living walls in three different systems, all in poor condition (including one using my older system); I’m not saying where or who because blaming is not appropriate nor my intention; rather, awareness raising is. The fact is that each and every system out there has good and bad examples to show. It is interesting to note that training efforts have been begun in at least one university, but this type of knowledge is a hands-on, college affair. Right now, it is only learnt on the job and this is art of the problem; many operatives simply don’t know their plants. If you don’t know the name, you’re not going to know anything about how it grows or when and how you should prune it.
My answer (and this goes much against my designer instincts) is to restrict the planting palette to those most able to survive. I always want to use more varieties, but it is sobering when you see them dying because they can’t cope with the conditions, or falling off the wall because the roots have been eaten by Vine weevil or millipedes. Beautiful grasses that have high levels of old, straw-like debris among the new healthy leaves are a no-no and geraniums may or may not look good in the winter months; such plants must be used with care. Patterned designs seem to fall by the wayside too; bold swathes are fine until one species fails and dies back, then you are left with a gaping wound.
So you may be thinking, should we do this at all? My answer is an emphatic yes, we should and must. We need to green the vertical in cities, for it is often the only space left available. We have all the needs of biodiversity, pollution mitigation and biophilia to account for and living walls provide those where no other greening method can – not even trees. We still have much to learn however, and the skill of maintenance has to be appreciated more by all involved. In fact it needs to be venerated and it’s practitioners respected and paid more.
Systems, at best second or third generation, need to evolve and be better understood. Or rather, plants need to be understood more, and their optimal needs met. We have, as I keep saying, hardly scratched the surface of what is possible and of what needs yet to be done. We need to learn more, try more and expect more.
There is something incredibly exciting about living walls. Stacking green plants on the vertical plane on buildings, where you’d think they just should not be, goes against the odds. Yet nowadays they are almost commonplace, and most people have encountered one somewhere. They cling to life with extraordinary tenacity, usually in a growing medium only a few centimeters thick, with water fed via irrigation pipes. Cynics may criticize and some walls are without doubt better designed and maintained, or use a better system than others, but we should applaud this urban green trend, and encourage it. We need it. Modern systems are reliable and use very little water or energy to run.
As a global society we are going through unprecedented changes; now more than 50% of the world’s population is urbanised and this will grow to 75-80% by 2050. Most of those people are essentially disconnected from Nature. It is now recognised that we have an innate need, called biophilia, to maintain our relationship with Nature. Not surprising really, when you think how we have evolved, yet the psychological and physical cut-off, over the last 100 years, has been astonishing. This can only become more pronounced as cities continue to swell, and highly-stressed people produce dysfunctional societies. If we can green our urban streets then perhaps we can counter this negative effect. Green walls take up almost no footprint in the urban landscape, not even a pavement width. All that is needed is a supporting wall and we have plenty of those. Trees are beautiful and add huge amounts of biophilic interaction into a citiscape, but we find them increasingly difficult to site, due to underground services and growing space needed. Those of you who read my blog will know that I also consult on trees, so I love them dearly, but I see living walls as having a different role to play and as being more versatile.
Living Wall in a small courtyard garden by Vertology
Living walls have physical benefits on the environment too. They provide a haven and food source for insects, especially bees. Birds find seeds, berries and of course, insects on the wall and smaller birds are known to nest amongst the foliage. Living walls are also helpful in mitigation of air pollution; I was involved with designing and plant selection for a wall put up by Transport for London (top picture) to test the ability of plants to capture pm10 – airborne particulates, primarily from diesel engines. Whilst we need to remove the source of these pollutants, capturing them is a good secondary strategy. It turns out that walls in a street canyon (where the building height is greater than the street width) cause the air to move in a cyclical manner, so air passes through the foliage of a living wall several times. Trees can do this, but dense canopies can actually trap particulates down at street level, concentrating them where people are. Most trees also are deciduous, so have no such benefits in the winter months.
Interior Living wall in Norway, installed by a Vertology partner
We can bring living walls into the interior, and in fact in hostile climates, that’s where you’ll find most of them. Whilst I have designed outdoor walls in climates as diverse as Dubai, Norway (Trondheim, 62° latitude) and Chicago, in such places it is often easier to put your dose of biophilia indoors! We spend 80-90% of our time inside, so this makes sense. Such walls also clean the air. Much quoted studies by NASA have shown that a range of common houseplants (which are basically plants of a sub-tropical origin) are efficient at removing Volatile Organic Compounds VOCs, such as formaldehyde) from the air. These can be found in concentrations far higher than outdoors, due to the nature of air recirculation and energy conservation. So we bring the jungle indoors, where we live and work.
Walls have the most drama when they are large, but they don’t have to be. Small walls in intimate spaces still have a large impact. This can be a home, courtyard, rooftop or office reception. Small is beautiful.
A small indoor living wall by Vertology
Having worked extensively with living walls over the last decade, I now consult, design and install them worldwide via my company Vertology Living Walls, and its approved partners. Grab yourself some biophilia – install a living wall!
Is there a “next place to go” for green/living walls? Absolutely there is – there’s probably two next places to go – in opposite directions, seemingly. First we have a growing need for the mitigation of environmental factors which are largely of our own making; air pollution, rising temperatures, storm and waste water management and purification. Methods of providing ecosystem services, if you like. We need these in urban areas, right at the heart of where the problems originate or concentrate. Linear, end-of-pipe solutions to things such as “waste” water (how can H20 ever be waste?) are becoming increasingly unaffordable, especially in third-world regions where the real population growth is taking place. So we need cyclical systems to deliver on-site solutions.
Global levels of air pollution. London looks good here, yet still fails WHO limits
Such systems must be cheap and effective. They will look green, be alive, but not driven by aesthetics, although that is not to say they won’t look good. But we need these types of wall to be installed an a huge scale, if they are to make a genuine contribution; with the climate changing so rapidly, we need all the help we can give ourselves. I’m working on such a system now, focusing on air pollution mitigation.
Vertical greening is particularly effective in the urban environment for two reasons: we have very little open space to implement large-scale greening on, and the effects of pollution are most felt in the urban canyon – where the sides of the streets (buildings) equal or exceed the width.. Greening the sides of urban canyons, therefore, has the greatest potential for capturing particulates (pm10 is the range causing most concern).
It is interesting to note that trees are often cited as being good at removal of dust and particulates – but green walls are far better. For a start, most urban trees are deciduous, so they only have leaves for seven months of the year, then there is the recently researched fact that trees in an urban canyon can actually trap particulates under their canopy, preventing the natural air movement from mixing pm10 into the larger air volumes. I work with trees and love them, so have no bias in this; we just need to understand the interactions between air movement and greening. So this for me, is the next generation of vertical greening technology. Interestingly, being next-gen doesn’t mean being more high tech. Given that things have to be cheaper, they have to be low tech but more effective. This is where understanding the effect of things is crucial.
The street canyon is the best place for vertical greening to remove air pollution.
I said that vertical greening developments would move in two directions; the other is for increased human interaction, for biophilia. As 80% of the world’s population will be urban by 2050, many of the projected nine billion will have little access to nature. We need to make our cities green forests – not the urban jungles they have become. Every building needs to have vertical parks and gardens built in as standard, giving us direct contact with nature (whilst at the same time giving us all those ecosystem services I mentioned earlier), which brings the two directions (function vs beauty) right back into one place. Furthermore, such systems must be easily retrofit-able onto existing building stock.
Vertical “biomembranes” give us vertical landscapes, satisfy our love for nature – biophilia and deliver ecosystem services
So there is a huge role for vertical greening to play for humanity, keeping us in a functioning, livable environment, giving us beauty, satisfying our need for biophilia and keeping us sane in an urbanised world. We’ve barely scratched the surface of what we can do and I’m certainly looking forward to upping my game with new products that take is in the right direction.
I came across an interesting article by Ruth Potts with the above title (http://www.thenewmaterialism.org/), which summed up pretty well where we need to be headed as a society to make the transition to a resource-scarce future. The crucial thing is, that this could be a much better future. Aren’t we all exhausted with the endless demands on our time, energy and finances that consumerism makes? In the run up to Christmas, how many of us are taking out loans or maxing out our credit cards to pay for the “pleasure” of giving, and how long will we remain in debt for that brief moment?
Christmas was ruined for me, only a few year’s ago, when I read that the quintessential Father Christmas as we know and love him, was “invented” by Coca Cola in the 1930’s (yes, I have now stopped believing!). Fortunately, that is not quite true (about Coca Cola), but there is no doubt that the figure of FC has been mercilessly exploited by commercial interests, and this gets worse every year. In fact, most retail shops now depend upon Christmas to make their yearly sales quotas and profit, so they are not likely to give up the “right” to promote consumerism any time soon.
You may wonder why I write about such things, since my interest really is focussed on vertical and urban greening; actually, my interest is in the survival of the human species and in the retention of a habitable planet, interests we should all have in common. At the core of our dilemma is not carbon emissions: in our typically linear-thinking, reductionist way, we focus upon these as the problem, when in fact they are a symptom of underlying factors. The biggest driver in all our systems is the act of consumption. You can figure out for yourself that there are only so many resources to go around and that the more people you cram into the world, and the more those people demand, the less there is to share out; sooner or later there will be nothing left. And we are hitting so many tipping points right now, we really should be far more concerned than we are, and should be taking far more action. Yet to mention it is almost taboo. We just don’t want to face it; it’s too scary. And what can we do, the little people? I would say quite a lot, actually. As an example, look at how Zara, one of the world’s biggest retail chains, has been forced to commit to producing toxic-free clothing, all within the space of a two-week campaign run by Greenpeace. That’s powerful.
Fact is, if we want a sustainable future, no; if we want a future, we have to kick the consumption habit, before it consumes us all. If we don’t, no amount of urban greening will make any difference…