Concrete is a wonderfully versatile material, which has been in use since Roman times and with it we can build amazing structures that would otherwise be impossible. Unfortunately it also carries a huge environmental cost, caused mostly in the cement binding used. Whilst gravel extraction is also an issue, for that there are some alternatives such as recycled, crushed concrete.
The production of modern cement (OPC – ordinary portland cement) is a hugely polluting process and produces around 8% of the world’s carbon emissions – at least twice that of the aviation industry. Whilst the Romans used a volcanic dust called pozzolona as their binding agent, until the invention of OPC, we used lime, in various forms. Lime too has to be processed by heat and so is not without it’s environmental cost, but it uses less energy to produce than cement and lime concrete/mortar reabsorbs carbon over its lifetime (if exposed to the air), offsetting some of the initial pollution. Moreover, because it is softer, materials can be disassembled easily, for re-use.
In a landscape, there is ubiquitous use of concrete in a range of structures – walls, paving, sub-bases, ponds etc. some of which could be reduced or avoided altogether. Whilst landscaping will always use an insignificant amount of concrete compared to urban development and infrastructure, there are good reasons to minimise the volume of cement and other hard landscape materials used.
Some of these reasons are for obviously sustainable goals: reducing material/resource input and carbon and other wastes. Equally important in my view, is to increase the soft elements exposed in a garden – soils – and to increase the levels of planting and foliage biomass/diversity. This thinking is about the increase of biophilic benefits.
However, if sustainability is to be given top priority – as it must – then the use of cement has to be reduced as much as possible. This is quite a challenge to us all, as it is not always easy to find an alternative and I don’t suggest for one minute that it should never be used, but it should be reserved for essential structural use only. Even then there may be alternatives. Recycled concrete can make a suitable aggregate (or part of) and low cement alternatives such as CEM 1 reduce the energy and carbon emissions tally.
I have used – and continue to use – concrete in many of my own designs and so this challenge is personal – but then aren’t all sustainability issues.
Let’s look at the different areas of the garden where cement is used:
Many walls use cement, either in mortar or in concrete blocks as well as in cement renders. In this garden (left) we built retaining walls using hollow concrete block construction on concrete footings with cement render and mineral pigments for the final colouring, with concrete paving slabs as coping. As the site was on a chalk hillside, it may have been possible to construct this using rammed chalk or earth. Indeed, we had a surplus of chalk on the site from the house construction and it would have made perfect eco-sense to have used this to build the walls. The walls could have been rendered using lime based mix, and the coping could have been stone. As the chalk hillside is inherently quite stable, rammed chalk could possibly have been used for the footings too. However, there are so many unknowns, and so few UK examples that it is a risk to do this, especially on such structurally critical terracing. Long-term effects of damp creeping into the walls would have been my main concern.
The cost of rammed earth construction may have been cheaper than conventional construction , both in time to do and in material purchase, especially when the removal off site of subsoil is taken into account.
The picture at right shows rammed earth walls in a sustainable landscape I designed for Grand Designs Live, ExCel, 2006. Rammed earth walls are made by compacting subsoil inside timber or metal formwork. The soil must be kept dry so it needs some kind of footing and capping, here provided by cast copings made with recycled aggregates and partial cement substitute (CEM 2 furnace slag). The gravel to the main paving area is a recycled brick/concrete mix, laid through a geo-grid membrane made from recycled plastic. The aim here is to be as carbon neutral as possible. Planting aspired to be edible (you can eat daylily flowers).
Walling alternatives to concrete include:
Cement alternatives/recycled aggregates
Timber walling (railway sleepers etc)
Round pole walling (preferably coppiced hardwood)
Fences & crib-type embankment walls
Brick/stone with lime mortar (brick also has high energy input)
Dry Stone walling
Modern paving is often made from concrete and in some instances it is quite hard to find realistic substitutes. Stone paving is the obvious one but can be expensive. There are many cheaper stone imports available these days, such as Indian Sandstone, which are cost-effective but which carry a high transport and pollution price tag. Reclaimed York paving is highly desirable and of course, reused, so environment friendly but will cost 2-3 times that of cast concrete or Indian Sandstone. Brick is also traditional as paviors but as for walling, still carries a high energy/pollution cost in production, plus is expensive to lay.
For larger areas and drives, self-binding gravels may be one of the better answers, as these form a firm surface, once compacted, without the use of cement. Recycled or local gravels are also acceptable and can be held in place using recycled plastic grids/membranes.
Paving is one of those areas which highlights the question of just what is sustainable. Is it better to use imported sandstone with its high transport miles but relatively low energy production, or locally made concrete paving with cement and aggregate use, but low transport miles? In either case, the (financial) costs may be similar. There are also ethical and human welfare considerations for stone imported from third world countries, especially in terms of working conditions, health & safety and child labour.
Timber decking can be a viable alternative, especially on sites with changes of levels. Local timbers of the more durable softwoods (like Douglas fir or larch), green oak, Sweet chestnut or recycled tropical hardwoods. All new timbers should be FSC (Forest Stewardship Council) certified. New hardwoods should be avoided even if the have an FSC certificate as there is much illegal timber that still gets sold and even managed plantations may still involves some environmental degradation. They certainly have high transport emissions.
Possible paving alternatives:
Recycled stone, brick, cobbles – and concrete slabs
Self binding aggregates don’t need cement
Fired paviors and tile look beautiful, but are still energy intensive
local or recycled aggregates and gravels
Decking can be used where appropriate
Locally produced concrete slabs minimise transport and can have lower carbon footprint than imported stone
Third-world stone may be low energy, but high transport emissions
Even natural looking ponds may use concrete in their construction and formal ponds may be dominated by it. Again choice of alternatives is limited.
Concrete is often used to retain rocks and place protective pads over liners, etc. In many places it may be possible to do without concrete pads, which are often used in a “belt-and-braces” approach to protecting a liner. Felt geomembranes are used as standard as a layer underneath and often inside the liner (this may in fact be degraded by contact with concrete) and in many cases, use of additional layers of felt may eliminate the need for concrete. Felt is usually a synthetic, petroleum based product, so also has its environmental considerations (as do liners!). I have successfully used old carpet as replacement for felt, under the pond (I wouldn’t recommend it inside) but be VERY wary of tacks that may have been used. Non-synthetic carpet will degrade over time, which must be born in mind. Of course, before the advent of felt, liners were simply bedded on a layer of sand.
Where rocks and stones create waterfalls, they are used to form spillways and to prevent stones moving when climbed over or stepped upon (an important safety consideration). It may be possible to use hydraulic lime based concretes for this, although I haven’t tried this out. Perhaps well laid rocks, without the use of cement are the key, which would require a careful re-thinking of the construction method. Nature doesn’t use concrete, but then natural streams don’t retain water within an artificial environment (liner). A more holistic approach to water features, where the roof water and household grey water are recycled and the pond design doesn’t hold a fixed level or amount of water, may be the long term answer.
So looking at alternatives to cement raise as many questions as answers and in the 12 or so years since this article was first written, there has been some progress, but not much. Best advice is to minimise the use wherever possible, recognising the long-term durability and benefits of strength that concrete possesses.
The safety of children and water is potentially a controversial issue and I want to make it clear from the start that these are genuine thoughts, with genuine intent but please don’t try and hold me liable for any disasters or accidents that may befall you or your loved ones. I cannot be responsible for your life and any decisions you make on this issue are yours alone. I naturally hope and intend that only good and positive benefit can come from this writing.
Children have an almost universal fascination with water, and parents
an equally almost universal fear of it, or of their children being near
it. We have all heard the horror stories of children drowning in a
pond, or even a shallow puddle and our hearts go out to those
unfortunate few who have suffered such a fate.
But we seem to live in a fear-driven compensation culture, which
stifles creativity or adventure because of the risk of hurt. Authorities
and companies cannot afford to take risks, or allow other to take them.
and more things get banned in the interests of public safety. The
world may be safer as a result but it is certainly blander.
As a young child I would walk the suburban mile or so to school on my own, ride my bike to visit friends, play down at the dump, swim in the sea and generally have freedoms many children are not now able to experience. But creative play is an essential part of a child’s development and must be catered for somehow. A love and respect of water should be encouraged and this requires contact and familiarity with it. I believe that those most at risk are those who do not appreciate the dangers and those who are too young to.
It is true, of course, that much of this familiarity, or lack of, will be caused by the geography of your environment. If you don’t have water in daily proximity, it is hard to become familiar with it. If you don’t see with your own eyes how a little stream can become a raging torrent after a downpour, then you will not be aware of the potential danger. Knowing the dangers brings about respect, gives us boundaries beyond which we know that things aren’t safe. In urban areas, the increasing use of WSUDs (water sensitive urban design) in the form of swales and rain gardens is a positive development.
There’s another good reason for us to have regular contact with water and that is a biophilic one. Water is a vital element, which, through modern living, we now tend to regard as no more than a right of utility. But water is the life force of the planet, and so of ourselves. Why else would we want it in our gardens? It soothes us, distracts us from our cares, puts us in touch with those deeper fundamentals of life, if we but let it. Children who experience this often can only be better off for it.
So if I’ve convinced you that it’s good for children to experience water, let’s think about how we might do so with some safety. First of all, young children should be supervised by an adult or responsible elder child, that goes without saying. I don’t advocate that you leave them alone. I don’t know if there are any statistics available as to the ages of children that have accidents with water, but parental sense will tell us all that children under five have little comprehension of danger and must be watched very carefully, as must those of all ages with special needs. Water features should perhaps be fenced off while children are in their early years.
If there’s not much you can do about water in your wider environment, then you can perhaps create a feature in your own garden.
Steep sides are the most dangerous aspect of a water feature, preventing children (and animals) from being able to stand up or climb out.
Loose paving on the edges of ponds is another risk factor; use only large slabs or stones and make sure that they have only a small percentage of overhang, and are securely cemented in place. Better yet, use a pond-edge design style which doesn’t use paving in this manner at all.
With gently sloping sides, layers of subsoil, gravel or shingle will protect the pond liner and give good grip for feet and hands – bare liner tends to be slippery and is more vulnerable to damage. Good construction helps all round, although that is not the subject of this article. If you have an overhanging deck, make sure the water is not too deep at this point and that children can’t get trapped underneath it. Metal or plastic grids can also be built into a pond, sitting just below the water level. These need careful thought as to their siting as they must take the weight of a person without breaking. The danger is these can look very industrial.
As a final thought, if you want moving water but don’t want the depth of a pond, consider a stream garden, where water just flows along a shallow water-course. There is no pond as such and the water just disappears underground into a hidden sump tank, which houses the pump and which is inaccessible..
In conclusion, there are many things that children learn from playing with water: self confidence, balance, awareness of danger, responsibility, experience of wildlife and of Nature’s rhythms. A careful and reasoned approach is what is required for allow a child safe, creative exploration.
And of course, we adults are all children at heart, too. Play safe.
Rain gardens are a relatively new approach on how to deal with water in the environment. In the last 10-15 years, there has been a big rise in the use of SUDS (sustainable urban drainage systems), the practice of delaying the entry of rainwater into the drainage system by the use of swales, ditches and ponds. However, this is generally the domain of engineers who are mostly concerned with their pipework; rain gardens, on the other hand, do the same thing, but are equally concerned with aesthetics and ecology – and so are far more exciting. Easily applied to the domestic situation, but the concept works just as well in urban and commercial design. In fact, WSUD – Water Sensative Urban Design – looks set to take on this wider role in the municipal environment, possibly replacing SUDS.
Having built many water gardens in my life, I decided (in 2010) it was time to build a rain garden in my own home, where I could enjoy it and also monitor its performance. These pictures show the just-completed garden, only a few months old; it also rained right on cue and appeared to be working well!
So what is the “philosophy” of a rain garden: why build one? Well, flood prevention is one answer; if you have ever experienced floods in your area, you have directly or indirectly contributed to them. If the rain didn’t fall on your actual roof, it fell on part of the urban fabric that has been built to support you. Another answer is to re-charge ground water supplies; many urban areas have groundwater levels that are dropping due to the fact that rain cannot permeate the land where it falls (95% of urban land is impermeable). Water tables are also dropping because we are abstracting water far more quickly than it is being replenished.
Rain gardens are a great way to re-connect with nature, opening you up to the experience of natural rhythms and process. It will sit there quietly in hot weather, dry, yet still a micro climate for flora and fauna that like a little extra moisture, in the lowest parts, providing free drainage to the drier areas. When it rains, though, the garden comes to life; water from the roof of your house, instead of disappearing down the drain, starts running into the areas of dips and dry ponds you have created, perhaps having topped up your rainwater butts first. Gradually pools start appearing and maybe in a heavy downpour, water starts running between them. How long it then takes to dissipate will depend upon your soil type; I’m on an alluvial soil, so it is very free draining; on heavy clay it might take days for the water to disperse, and this might mostly be from evaporation. This is good too as it helps re-charge the local hydrological cycle, which is also severly lacking sufficient moisture content, and may well be a significant but overlooked driver of climate change. If you have limited space or can’t allow water to rise beyond a certain level (after all, you don’t want to move the flood potential from somewhere further away, to your own home!), then you might need an overflow which puts any surplus water back to drain, or perhaps (and preferably) to another part of the garden. You will have still considerably delayed the timing of water going to drain, as well as the volume.
In my garden, I have disconnected one of the main roof downpipes (which it turned out was blocked) and used an old steel channel I found when they demolished the adjacent dairy. We have old cast-iron downpipes so I bought a 90° bend and fitted that to direct the water into the chute. I then dug a channel and partly lined the bottom with plastic, because our ground is very free draining and I wanted to connect this to an existing small water feature, so that this was topped up by rainfall. Surplus water is then dispersed to the sides, through the planting. If I were designing this from scratch, I would put the pond before the raingarden, so this was topped up first. Having said that, this section of the garden has always been incredibly dry and I’m hoping that the ground will, over time, recharge itself and things will grow better. This dryness is evidenced by the fact that we have a young fig growing well, right by the downpipe.
In periods of heavy and prolonged downpours, it may be that the pond will overflow; this will happen at the back and will disperse out away from the house under the bushes. With our soil, I don’t see the need for any further overflow drainage.
The roof section that feeds this downpipe is about 50m2, south facing. We get on average 50cm rain per year, so this should capture 25m3/year. This morning in light/medium rainfall, the chute was delivering 3 litres/minute (nowhere near the rate of a hosepipe). The rain garden is about four metres long and I’m not sure how to measure the drainage rate of soil, apart from having the plasticity index measured in a lab but over time I will use these figures to try and calculate how much water is passing through the system; in theory 25m3/year.
I was sent this picture (right) of a rain garden I designed for a client around the same time that I made mine. What a great picture, it gets right to the heart for so many issues about life, play, learning, experience, the elements. We tend to over-design our environments for safety, yet end up sanitizing them to the point where life becomes uneventful and we loose the richness and diversity that being connected to nature gives us. On a rainy day most kids are sat in front of the TV; I think this as a much better option…
The soil in this raingarden is a heavy clay and so holds the water for longer. It is bigger than mine and would need to be to increase the percolation area. You can also see that mine is more planted and this is again a condition of its function – theirs was designed to be a play space for the children (which is why I’m so pleased that it is successful). When they have grown up, it can be planted more intensely. It also created a feature in an otherwise rather awkward, narrow, North-facing space.
Rainwater management isn’t just for large commercial or public-realm sites, it can be done in your own garden too, with multiple benefits to environment, garden, wildlife and of course, you.
The emergence of the idea of resilient planting is a response to a number of different pressures which all have one underlying cause – climate change. Whatever the cause – and I’ll get on to that later – I see it as the most exciting change to the way we design our gardens and landscapes.
Last year we had one of the hottest summers ever recorded and it serves to heighten awareness of the vulnerability of some plants and garden styles to the increasingly erratic climate we are dealing with in the UK. We seem to swing from one extreme to the other, and this is only likely to get worse. I’ve witnessed a number of stressed plants in my own garden but feel relieved that most have thrived throughout the heat, without any watering on my part. this is down to soil, drainage, micro-climate and above all, plant choice.
Ballota pseudodictamnus, a Mediterranean sub-shrub with grey, felted leaves, loved by bees.
We garden on an alluvial coastal plain, and are fortunate to have a very free-draining soil overlying a clay substrate. It gives us fertile soil, great drainage and a moist sub-strata within the reach of most plants (many areas around us are of much heavier clay). A large section of our front area used to be a paddock with a rubble driveway and this now forms the basis of much of my dry garden. Some rubble was removed and topsoil added, but a lot of areas are still rubble-strewn, not unlike some rocky soils. The down side of all this is super-fertility and a soil filled with weed seeds, bindweed and couch. To be honest, I’d have preferred a poorer soil.
When thinking of resilient planting, we have to match our plant type to the environment; we also have to think, long-term, of how our environment might change in the coming years. This is not so important when dealing with short-lived plants such as herbs, sub-shrubs and perennials, but is super important when dealing with long-term structures, especially trees. This is doubly true when we look at the potentially disastrous effects of imported pests and diseases that we are having to content with. Climate change, especially milder winters, mean that exotic pests are happily making a home here and wreaking an unintentional devastation to trees such as our native ash and even oak.
Phlomis russeliana, after flowering. The stem leaves have since dropped, leaving a brown, architectural structure.
No-one can say exactly which way our climate will go as the world hots up; we know we (in the UK) will always be maritime, because that can’t change, but as the Jet stream (wind currents) varies and the Gulf stream (water currents) weakens, we don’t really know what kind of climate we’ll end up with. We can only plan for extremes, and select our planting choices with that in mind. In this respect, the “new perennial” or “naturalistic” planting isn’t necessarily going to be the toughest choice as they come from a continental climate which generally have hot summers and very cold winters. Prairie plants tend to get out-competed here with our mild winters and grasses and forbs that can grow all year round, given mild conditions. The aforementioned fertility (at least in my garden’s case) also doesn’t help as wildflower meadows/prairies tend to have poor soil which helps keep the grasses from assuming dominance. During the heat-stressed weeks, I noticed that where I have perennials like Echinacea and Veronicastrum (in moister areas than the dry garden), they suffered from the lack of water. which resulted in the Veronacastrum flower spikes looking stunted. for more moisture-demanding planting, sub-surface irrigation using harvested rainwater might become a necessity.
To my mind though, if you need irrigation you’re working with the wrong plant-types, trying to grow plants that can’t naturally cope with the conditions that predominate. Save your water for the newly planted and the vegetable plot and for this, consider rainwater harvesting, rather than mains. When selecting plants, see what grows well, both of native and non-native origins and build adaptive micro-ecologies. Our climate is changing faster than the current ecosystems and ecologies can cope with and we need to do whatever we can to build new planting that is of maximum benefit to local wildlife, as well as ourselves.
It’s an exciting time to be a gardener, for there is no place now for the self-indulgence and nature-control-freakishness of the past. What there is a the possibility of co-creating new ecologies that adapt to changes, halt decline and make our local wildlife vibrant and healthy.
Along the way, we can create the most stunning of gardens!
There are few aspects of our built environment more emotive that that of the entrance door. It can mean shelter, warmth, food, security, friendship. All of life involves the act of entrance, from the earliest caveman to the present day.
How many times per day do we go in and out of buildings and our homes? We scarcely stop to think about it, yet entrances all convey subconscious messages which can affect us on deeper levels, for good or ill. Some doorways are enticing, friendly; some oppressive; some just dingy and neglected. Most are probably functional and non-descript, of itself a message just as powerful as the others.
We move from our homes to cars, to shops, offices or other houses. Each time we do this we experience a subtle shift in light levels, humidity, warmth, expectations and intentions. Our mood shifts and adjusts with our purpose and our expectations. Going to work we might subconsciously don a mask as we enter busy offices or a large railway station. Arriving home again, we relax as we walk up the path, shedding the mask as we close the door behind us.
A Wisteria-covered pergola gives a deep connection between the kitchen door, driveway, outhouse and rear garden
The physical structure of a building and its entrances tell us what to expect: grand doorways with tall columns tell us of status, power and authority. Grim entrances to prisons have an unmistakable message. In public buildings especially, proportion is everything, where tall ceilings and doors give formality. By contrast a humble cottage door or an old garden gate recessed into an ivy-covered wall might look secretive or inviting, asking us to explore the spaces beyond. What do the doors to our homes tell us? Most front doors are rather bland or feel inauthentic, for example the many mock-Georgian style doors on modern houses offer us nothing more than a thin veil of pseudo-style applied over a nondescript structure.
In the home, layout and door position is also important. The front door is our formal entrance to the world, the back for our private comings and goings. Yet how many house layouts truly observe such simple criteria? Some houses have both the front and back doors equally visible, with no clear indication as to which is which. Or the back door opens onto a narrow side passage, rather than directly onto the garden. Many of us live with awkward house layouts.
Overcoming the problem of awkward flow is, however, fundamental to the harmonious functioning of a house and its occupants. On occasions when looking at a house and the way it connects to the garden, I have recommended the re-location of the rear door. It sounds extreme but I have had several clients who were very glad they took my advice. Fundamental problems sometimes need bold solutions and the picture below is one such example. Here, a new connection from kitchen into the garden via a (new) seating area made a big transformation.
New French doors give connection to the garden, creating a new experience in this house
French or patio doors aren’t always the bonus they’re meant to be, though. Sometimes these confuse the traffic-flow and can destroy the usability of the room in which they occur. Lines of movement (inside or out) should not cut through a still-point. Of course, sliding doors which truly open up the house and invite a more relaxed transition can be fantastic. It’s all down to careful thought and good design.
So much for placement, what of the physical act of entering and leaving? All too often it’s a bit, well, abrupt. Ground and wall meet at the perpendicular, at which point, there’s a door. You open it, go in or out. That’s it – all over with. Yet it takes a moment to adjust, from one environment to another, both physically (light and warmth) and mentally (tasks, purpose, relaxation). Ideally therefore, we need a space in which to adjust, to experience transition, even if it’s for just one second. That space becomes an area that is “in-between” – it could be a porch to the front entrance or a pergola to the rear. A covered walkway might lead to the car, a path or set of steps might connect us to the garden.
How this transitional space is styled will of course depend upon its use. For a front door, nothing beats a good porch or recessed doorway. The visitor waits in this transitional space for the door to be opened, the owner pauses to find their keys. Both might be glad to be out of the rain, or bathed in a welcoming light at night. Where possible, the porch should be preceded in the approach by a path and suitable planting, building up the sense of arrival. In these days of open-plan front gardens, attention to these simple things can make a big difference.
Where a door fronts onto a street, a roof canopy over the door and some tubs or wall planters might serve. A step up onto a different level might be frowned upon by planners, but where disabled access is not an issue, a step up, off the pavement can make a huge difference – suddenly we are in stasis, out of the busy flow of the main path.
To the rear, where a door connects you to the garden, there are multiple ways to enrich the experience of transition. A pergola might frame a door and be part of a larger structure which defines an outdoor room. Conservatories and lean-tos might be the connecting space. Loggias and verandas make a great transitional area. Where the back door has to be to the side of the house, perhaps make a shady passage covered by pergola, with ferns, foliage and climbers to give dappled light. Choose a good brick or stone and make it feel like a tunnel leading out into the garden proper.
So think about the way you move in and out of your house. Imagine the use, mood and character you wish to create and then find the structure to answer that need. A good entrance can really root a building into its environment and enhance the user experience considerably. If a building feels settled, like it belongs, you will too. Don’t put up with the merely adequate – enrich that transitional moment and rediscover the lost art of entrance.
This was first published in 2009 and is referred to in Wikipedia.
Curves are an integral element of design and especially of landscape, since they make a connection to nature, which does not use linear form. Curvilinear lines are notoriously difficult to achieve as they are invariably of a freeform nature (ignoring geometric curves which are formed by arcs) and are subject to interpretation “by eye” of the person setting out the design. A few centimetres either way can however, throw a curve out, disrupting its harmonic flow.
As someone who designs a lot with organic, freeform curves, I have seen horrendous attempts at setting out curves by contractors who are nonetheless competent in every other respect. It’s not about ability so much as a certain way of seeing things. Perhaps drawing curves that work is the ultimate test and definition of a good designer, whilst the successful setting out of curves on the ground or in three dimensional form separates the artist from the builder.
It’s easy for me to say there are good and bad curves, quite another to explain and illustrate the difference. I have been wanting to write this article for a number of years, but so far put it off because of the difficulty in describing something so abstract. However, understanding curvilinear form is crucial, so I will try to explain something that is for me instinctive, rather than intellectual.
Let’s take as a starting point the difference between intellectual and instinctive design. Intellectually, you might form a series of circles and form a connecting line whilst instinctively, you might just take a pencil and draw a flowing line. The former is precise, controlled, intellectual, inorganic, whilst the latter is instinctive, free-flowing, emotional, organic. This is illustrated at here: need I say which is which?
The left hand curve would be preferred by any contractor setting out a garden: provided he gets the centre points in the right place, the rest is simple. the right hand curve requires personal judgment of eye; it is subjective and so much harder to translate from paper onto the ground.
The right hand curve is alive; it has rhythm, flow, it feels right. The other curve simply jars the eye, it is dead, with no movement.
It is true, however, that not every freeform curve is successful. In nature, animals (and Man) move in curved paths, plants follow curved movements, water flows in spiral vertical pathways. All these have a natural rhythm, and for our freeform line to succeed, it must do likewise.
A centred line running through the curves with offset measurements is the best way to translate this from paper but it is still easy to get this wrong, in the manner illustrated below.
Curvilinear form – right and wrong
curvilinear form – variations of line
The freeform line at top left shows two possibilities: the red line is smooth, flowing, but the green line flattens across the natural line of the curve. It is still a freeform line but it no longer feels fluid and loses its sense of movement. The variation from the red line might be only a matter of inches/centimetres but it is enough to disrupt the visual flow.
To make matters more complicated, there is seldom just one exact freeform line that is perfect for the situation: in the drawing below left, all of the different lines will do the same job. What determines the correct one is likely to be the relationship of it to other nearby elements. Perhaps the most common mistake is to use too many tight reverse curves – to put in too many “squiggles”, in other words. On the whole, reverse freeform curves should not be too severe or exaggerated.
Plan showing a curvilinear setout
Let’s look at how a predefined space determined the use of curvilinear form.
The example at right is (part of) a beach garden I designed a some years ago. The yellow area is the boundary wall – a massive concrete sea defense wall 700mm thick. The kinks and angles in this wall left a space that provided no internal parallels and could only be fully resolved using curvilinear form. The area adjoining this (not shown) was linear in format, as the space there invited.
Running all the way along the inside of this boundary wall was a seat, again of massive concrete. This needed breaking up with the introduction of planting beds, leaving small sections of seat in between. The red line represents the nearest linear form that could have been used but you can see that what it describes is naturally curvilinear in nature (the green line). Don’t forget that all curves are made up of straight lines (curvi-linear)!
The design uses freeform lines to reflect the boundary wall and a spiral acts as a beginning, or end, at the point where most sitting out occurs. This is what I call a “still point”, whilst the main flow of the paving, leading to the adjacent garden, I call a “line of movement”.
I do not believe that this area could have been resolved so well using linear means. The main point to note, however, it that the lines had to be freeform: geometrically derived curves would not have worked, although the contractor would have preferred them! I had to assist in the setting out, but once done, a superb job of construction was carried out. The walls were rendered with a specially textured cement based render, which was ideal for the tough coastal conditions.
dealing with curvilinear form will always be more problematic than linear, or than curves set out using radii. The rewards are however, subtle and infinitely powerful if you get it right.
A problem, or an opportunity for a new landscape paradigm?
I was recently working on a tree project in Abu Dhabi when I came across a derelict site which intrigued me with it’s range of exotic self-seeded, non-native plants. The site was next to the Corniche and sandwiched between the Formal Park, my hotel and Capital Gardens. It struck me initially as the perfect basis of a xeriscape, as all the plants (mostly trees) were thriving without irrigation. On closer inspection and identification of the species involved, things got more complex and raised a lot of potentially conflicting thoughts and issues.
A natural Xeriscape
The site was clearly awaiting redevelopment and the plant invasion was opportunistic. Nothing that I could identify was native, yet all seemed happy there. When you see the list, you might understand why. Amongst the plastic and litter I identified:
Of those plants, the P. juliflora was the most robust and when you look at its reputation, that is of no surprise. It was of landscape scale, lush and greener than anything in the adjacent parks. It’s form, leaf, flowers and seeds are attractive from a landscape perspective. Yet this is undoubtedly the most controversial plant on this list – some would say alarming. A Native of arid zones in central and South America, this was, like so many others, introduced into the UAE in the 70’s as a forestry plant. Lauded as something of a super-crop tree, it is tenacious, vigorous, provids fuelwood and stock-feed in the form of abundant seeds. The latter, it turned out, were a problem in that they are spread by cattle and are extremely aggressive. Plants also regenerate rapidly from the roots when cut back and they reputedly produce biochemical inhibitors to suppress competition (allelopathy). With no natural competitors in the UAE and roots that can descend 50m in search of water, they out-compete native flora, even their cousin, Prosopis cineraria (ghaf tree).
Prosopis juliflora flowers
P. juliflora has a low, mounding habit, attractive from a landscape point of view.
Also on the site were a number of Banyan trees, Ficus benghalensis, which seemed to be growing happily. Another tough survivor, it should be borne in mind that the water table here is likely only a metre or so below ground, although it will have a high saline content.
Then there was Eucalyptus glaucescens, another forestry/amenity introduction of the 70’s, also known and now generally avoided for its aggressive roots, yet here looking beautiful with its grey, lanceolate foliage. This was the tallest tree on site.
Eucalyptus glaucescens, showing adult foliage
Of course, there was the ubiquitous Conocarpus lancifolius, widely planted still yet also recognised and a danger to any nearby drains, and on it’s way out in popular use. Except it does make such a good tall hedge, and it has a much nearer native origin, coming from Somalia, Djibouti and Yemen. I’m not sure that the UAE landscape industry is ready to ditch it just yet.
There was even a palm, Washingtonia robusta, self-seeded around the place. Much of it was to be found growing underneath the canopy of the P. juliflora, so that at least is not put off by any allelopathic biochemicals from the Prosopis.
There were also a few unidentified things, this shrub, for example. A legume of some kind, if anyone can ID it, please let me know.
Inhabiting, or at least visiting the site, was a Rose-winged Parakeet. Another exotic invasive with beautiful form but aggressive tendencies; it seemed appropriate to the moment, somehow.
What does this mean for future landscapes and ecology?
From a conventional ecology point of view, these plants are all threats, and the threats probably outweigh their usefulness. So why am I even talking about this? Clearly, the move towards more naturalistic landscapes draws heavily on native species and would shun all of these species.
Except we have climate change.
Climate change is the elephant in the room, when it comes to ecology, in fact when it comes to sustainability generally and a livable planet overall. That we have already moved beyond vital tipping points is highly likely; that climate zones are moving away from the equator at a rate too fast for nature to adapt is a fact. Flora and even some fauna just can’t move regions that quickly. They will adapt, eventually; but those that are rare, specialist and struggle with change, will die. The tougher generalists will adapt and survive. Nature will build a new ecology to reflect the new reality, and it doesn’t mind if it takes a few thousand years to do so. Only we humans mind and so, if we are to survive, we must adapt our environments to fit the new reality. It is a sad fact that many cherished plants will eventually die out or move zones. In the UK, I dread losing our native oaks (I view these as our ghaf tree equivalent), yet we may get Mediterranean species to replace them, such as holm and cork oak.
If you are already positioned in the arid equatorial zones then you have precious few plants that will form your new ecologies and landscapes. Perhaps the plants I have described above will be UAE naturalized-natives in 100 years’ time and the ghaf and sidr may be gone, or diminished, or moved north. I hope not, but before we spend vast fortunes on eradication and control of non-natives, we should look to the future. These aggressive invaders may just form the landscape of our children; I know I’d rather live with a landscape, than none at all. If there is no landscape, there is no life. They may, in fact, be here to save us.
Once we grasp this fact, we can look at building new landscapes to suit our changing environments. I’ve written about this before and you can read the articles listed below. We must be vastly more holistic in our thinking in order to do this and broaden our horizons to understand the new future. Technology will help us to monitor, collect data and produce working strategies. Robotics and drones will help manage and control plant communities. Alongside that, we need a vastly better understanding of soils, microflora and fauna, for the bit of nature that we see is just, literally, the tip of the iceberg. The selection of tree and shrub species for adaptation is easy, we get this wrong when we don’t deal in whole context thinking eg. only thinking of forestry or ornamental benefits.
The challenge ahead is huge but in a weird way, exciting; it will challenge the human race to grow. There’s a whole new science to develop and we’d best get on with it.
On my most recent trip to Dubai, I enjoyed walking through some of the new landscapes that emerge as projects are completed. The UAE, along with most regions of the Middle-east has a rather limited palette of plants to work with (although that is growing as new plants are tried). What struck me, however, was how poor the quality of nursery stock was in some cases and what problems are being created for later, especially with regards trees.
This is not new, nor confined to this part of the world but it bothers me that new areas of urban green are sometimes given a poor start with sub-standard nursery stock, often flown in from other parts of the world.
Simple pruning at an early stage would have improved this tree’s framework, removing crossing and rubbing branches.
Wandering around a residential area in Jumeirah, I came across some newly planted Delonix regia, one of my favourite exotic trees. At first glance it looked nice, a simple planting of trees and groundcover but on closer inspection I was somewhat dismayed at the condition of the them. The problems of poor framework were caused by their time in the nursery, not due to planting, although some of them could have been rectified by a vigilant planting crew.
This tree tie – complete with post – must have been like this from the nursery. The post did not reach the ground.
Many of the dozen or so trees had ties left on which the tree had grown around completely, making them impossible to remove. As the planting is only around two years old (by my estimation), these may have been on the trees from their time in the nursery. Possibly the planting was older and pre-dated the building they were attached to and the trees then grew around the ties after planting. Either way, it’s a strong indication of neglect or lack of care. In the picture below, all the bark ridge above the tie may indicate “included bark” – bark sandwiched against bark, preventing live tissue growth and a strong branch collar formation.
The tree tie is trapped with “included bark” at the branch collar, which indicates a potentially weak branch join.
Several problems are arising here: pre-planting care in the form of correct formative pruning (five minutes with a pair of secateurs) and Post-planting care in terms of releasing planting ties – if they were not simply left over from the nursery days. If there is no way to go back and release the ties, a bio-degradable tie should have been used.
This Ficus nigra was most likely damaged long before it was planted in this location.
Damage to the main trunk or structural framework of a tree might go unnoticed when the trees are small but cause major problems as the tree gets older and puts on size and weight. This can range from the cosmetic to the potentially dangerous in a large tree and at this stage the remedy is costly and the expertise hard to find.
As fast-growing cities like Dubai mature, the needs of landscape shift from creation (in a hurry) to maintenance (at a constant pace). Skills, awareness of the need for – and absence – of skills, will become more and more urgent. If Dubai wants to keep it’s beautiful, green mantle, then there is a whole new phase of arboricultural care awaiting to be discovered and initiated. I have carried out trees assesments and given basic training of correct pruning methods in the UAE, but that has hardly scratched the surface; there is a lot more to be done.
Trees are the urban, biophilic, blanket that clothe and surround the concrete mountains we build. Trees make hot places not just bearable, but unbelievably beautiful. Trees absorb dust, cool the air, add moisture and oxygen and enrich our Souls. We need to honour and look after them, so that they can look after us.
The way in which we design, create, maintain and use urban landscapes is likely to change radically in the next 15 years (in fact, modern society is in for overwhelming change). Urbanisation, climate change and the rapid rise of technology and artificial intelligence (AI) will see to that. Don’t think that the rate of change will be the same as has occurred in the previous 15 years, for technological growth is on an exponential growth curve, not a linear one. Cities and systems are becoming smart, connected to the Internet of Things and that is just for starters. So how will this change the way we design and use our urban landscapes?
Firstly, we know that there is huge movement of populations from rural to urban life, especially in the developing worlds and most markedly in Asia. This creates huge pressure for new urban infrastructure and this is not always well planned growth, especially in terms of forward thinking to account for future changes. Nonetheless, it is happening and happening fast. The UN expects 66% of the world’s population to be urban by 2050, by which time there will be 9bn of us – so 6bn in cities. Mega-cities have to grow in a way that sustains huge numbers of people.
Secondly, climate change is also occurring at exponential rates, raising the difficulties of living in any environment but with especial problems for mega cities, most of which are in coastal regions and subject to rising sea levels and worsening weather patterns. Cities are hotter than the surrounding land due to the nature of materials used, whilst heavy rainfall brings flash-flooding. In arid countries, built environments are in danger of becoming too hot for humans to inhabit. Cities will have to take on these challenges, generating micro-climate.
Thirdly, technological change is happening exponentially and this will impact what we do, how we live, how – if – we work and how we tackle the above problems. Some view the challenges and changes with fear, thinking they will only exacerbate problems. They could do, anything can be mismanaged (such as a planet) for example. I foresee that technology is actually the only way we are going to get ourselves out of the mess we have created, the only thing that can act on the vast scale needed to re-balance an out-of-kilter Gaia.
When we take these three factors into account, we can see that the future of urban landscapes has to be so much more than the addition of the odd pocket-park here and there. Landscapes have to mitigate the environmental factors, make huge mega-cities liveable for a population increasingly disconnected from nature and provide meaningful lives in an era when many of us may not work in the way we are used to.
Weedy and neglected landscape plantings are all too common. No-one wants to pay for maintenance
How will cities become smart and use this to better the environment? If we are looking to increase the amount of urban landscaping significantly, then the first issue to tackle is cost of maintenance. No one wants to pay for maintenance and often, no one does. How many planted landscapes do you see smothered in weeds, wrecking or negating the designed purpose? Or municipal plantings and car-parks where plants inevitably die and are never replaced, leaving huge gaps. Shrubs hedge trimmed into amorphous shapes because that’s the quickest way to “maintain” them. It’s a poor standard and it’s all we’re going to get – no-one is going to pay for trained horticulturalists to do something better.
Landscape lobotomy: maintenance is the quickest, cheapest possible
Yet there is an interesting possibility – automation is likely to remove nearly 50% of jobs in the next decade, especially low-skilled or repetitive ones. In the landscape trade, there are already semi-autonomous strimmers and grass-cutters on the market, how long before we have horticultural robots maintaining our landscapes? All the technology is already here, prices are falling and an uplink to an AI would identify every weed known, give the correct procedures, know how and when to prune every plant in common cultivation. Robots would work long hours without tea breaks! If basic maintenance getters a lot cheaper, we can have more landscape and such robots would be cheaper, eventually. Living walls would be a prime candidate, with a simple maintenance cradle (much like a 3D printer head) that crosses the wall with a maintenance bot on it. I’ve seen so many potential living wall projects fall at the maintenance-cost hurdle. In such a scenario, displaced maintenance crew can retrain as bot-supervisors or true horticulturalist for private clients.
Horticultural robots will make maintenance cheaper and more effective.
We’re going to have to do more than just make maintenance affordable; rather, that is the factor that releases the possibility to do more urban landscaping. Many of the elements we need to put in place are already in existence and being used, but we need to join the dots and think holistically. For example, green roofs are seen as a separate trade from green (I prefer living) walls. Instead, we need to be talking of biological membranes (biomembranes) for buildings, a whole-system concept, where the living skin regulates the internal environment, filters pollution in both directions, dealing with generation of energy, cooling, clean air and water. Living walls that currently use potable water for irrigation when they could be cleaning up the used greywater that all buildings generate is another example.
Building Biomembranes regulate building ecology and create vertical landscapes
Systems that provide services that are of consequence to the functioning of a building, street, or neighbourhood need careful management and control, much of which will become automated. In just the last year, for example, new irrigation controllers have come on the market which not only are connected to you via internet, they also connect to the nearest weather station and adjust their regime according to the conditions. I use these for living walls; I do not advocate any irrigation for horizontal landscapes in temperate climates. But things will move beyond this, with AI monitoring ground moisture levels and moving harvested rainwater from one holding system out to another part of the city where it is needed. And urban farming – especially vertical – will be a large part of mega-city greening, although it might not be on display. Sophisticated hydroponic systems are springing up in warehouses and roof-top polytunnels all over. Such food can and should be organic, local, healthy, nutritious.
A smartly connected landscape means we can maximize the benefit it gives to the people who live, work or pass through it. With the majority of people living in urban mega cities, we have to create an environment that is fit for ultra-dense urban living. As these metropolis’ grow, people will have less and less daily contact with Nature, which is not good for our deeper wellbeing. Biophilia is our innate need for contact with the natural world: plants, trees, flowers, insects, sunlight, water, earth. A concrete jungle is not a substitute for the real thing but we mostly won’t have time to “get out there” and experience wild Nature.
I think inner city pollution will blow over – excuse the pun- in the next 5-10 years as we start a massive switch over to electric transport, most of it driverless. In fact, drone taxis are already under development and as buildings and living habitats reach skyward we can expect the landscape to move with them. It will become commonplace to have high-level dronepads – even private ones. Some people might not even go down to the ground much! So landscapes and biophilia must come to them. Fortunately, there is a rash of building-integrated vegetation going on and I see this trend increasing. Incidentally, if you wanted more good reasons for using bots to maintain planting, imagine working on living walls or trees that are 50 stories up!
As for the wider environment and the looming crisis of climate change, I can only hope that emerging nanotechnologies give us the tools to clean up our act and neutralise the positive feedback loops we are creating. Scientists are already working on nanotechnologies which capture and convert carbon into useful materials and one day such microscopic machines may roam our land and seas, removing plastics and other dangerous waste. If this is done at a molecular level, we turn problems into resources. We’ll be printing our houses (already being tested) compounds made from waste materials but without the current worries of using say, bricks made from recycled plastic which off-gas VOCs. We can only hope these technologies emerge before it’s too late to save the climate in a state that we can survive in.
So the next 10-15 years are going to see change at an unprecedented rate and it may not all be a smooth ride. I am excited by it however and think that there is much to be done to ensure that we create new urban environments worthy of habitation and that we take care of all environments and indeed the whole planet. Smart cities are coming and at their best they could loosen our imaginations and liberate us from a monotonous life of work and stress. Let’s make that the scenario that happens…
This article first appeared in Pro Landscaper Gulf – a .PDF copy can be seen here on page 12. It is based on tree consultancy work I have undertaken in Abu Dhabi in recent years.
Irrigation is taken as a necessity when landscaping in arid climates. It is a view that I wouldn’t like to completely contradict, yet I have seen a fair bit of evidence that tells me many plantings, and trees especially, are over-watered. Of equal importance is the fact that many of the irrigation methods are wasteful of water and sometimes damaging to the trees themselves.
Lawn Watering with sprinklers is damaging the trunk of this Millingtonia
We have to discern the different needs of trees and understand that what is necessary for one species is overkill for another. I particularly speak of natives verses exotics. Ghaf and Sidr you will see growing wild and without irrigation but imported exotics need a regular supply. I have seen Ghaf blown over in irrigated plantings, caused by shallow rooting from an easy water supply.
Bacterial wetwood in Delonix regia caused by overwatering. It also reduces the flowering, for which these trees are famous.
How the water is put on is just as important; pop-up sprinklers in lawns can damage the trunks of trees, causing aerial rooting in species like palm or fig, discolouring bark and causing stress-induced rots to occur in others. Exotics like the Flame tree (Delonix regia) get over-watered, causing a reduction in flowering and a susceptibility to bacterial wetwood (slime flux). Even drip irrigation is not ideal, as it applies the water at the surface and promotes shallow rooting. Trees with shallow roots are vulnerable to drought and so dependent upon the irrigation supply – a vicious circle.
Excess surface irrigation is wasteful.
In the UK, we are used to putting in a subterranean irrigation ring around trees, which gets water to the tree roots at a deeper level. For watering established trees, perforated tubes can be utilised, inserted vertically throughout the root zone and either manually watered, or connected to standard irrigation systems. Supplying water at a slightly deeper level means less water used and wasted. A word of warning though – most feeding roots occur in the top 300 – 500mm of soil, so watering too deeply can also be wasteful.
Tree roots growing along the line of surface irrigation pipes
In coastal cities, problems can arise from a naturally high-level, saline water table. Halophytes (salt tolerant plants) have evolved to cope with this, but for some imported species, salinity can be a problem. You also have to be aware of the quality of the irrigation water itself, which if drawn from the ground, may have a high saline content. Get your water supply tested if you are unsure.
Ultimately, I believe that planting styles and expectations of “landscape” must change. A more natural style, with more xeriscaping and use of natives or other arid loving plants from different parts of the world (but from similar conditions), will emerge. More important, in my view, than using strictly native species, is building plant communities that function and thrive in place without much human care or maintenance. As climate zones shift rapidly around the world, nature cannot keep up and it will be down to us to create landscapes that sit well in their altered environments, whether native or not. I believe we can do this with considerably less use of irrigation. The water we do use should then be grey water (from taps and sinks), which is a much better way to conserve processed water use.
Canopy of Delonix regia
The goal has to be minimal water use, natural, ecologically benign planting and urban environments which feed our biophilic needs for connection to nature.
Zizyphus spina-christi, crown of thorns tree. A native of the UAE