This is a subject that is very dear to my heart. I get quite passionate about the subject so do apologise if I offend any readers. I have been a sustainable garden advocate now for at least 20 years – well before most people even considered what sustainable gardens really meant. So I have put a lot of mental energy into working out why I think the way that I do about how we design gardens and how we manage them into the future. I was also the only owner/designer of a garden that was accredited with Ecotourism Australia for its sustainability credentials.
Excellent examples of sustainable gardens are often Botanic Gardens, the Adelaide Botanic Garden in particular being a very good example. I spent much of my childhood wandering through this special place, learning a respect for different plants and their juxtaposition with each other. It was never about hard landscaping – it has always been about plants. And this to me is what maketh a garden.
Many of the designs being portrayed by students from landscape design institutions are to me evidence of ‘learnt design’, not natural instinct. My instinct will always be to use the site as is presented, even with a difficult slope. This then enables natural movement of water over the site, without having to reconstruct a drainage system to manage storm water.
Am I being old-fashioned? Some, in fact many, may say yes, but my clients when shown pictures of gardens that are award winning ‘sustainable’ gardens, always claim that they want more plants with a far greater variety of plant material used. The real sustainable advocate understands the need for biodiversity in all of its forms, especially plants and trees that encourage different birds, insects, lizards etc. Not just one or 2 plants, but a mass of them providing understorey as well as canopy.
In order to make this garden that some may find boring, because of the lack of the trendy outdoor room, brazier pit, painted panels and so on, I prefer the more subtle use of receptacles for bird baths, quirky sculpture, recycled bits and pieces from the site that can be used to make its own ‘picture’ when grouped together. These ideas are classic and will last indefinitely, whereas the outdoor rooms, with all of the maintance that is entailed will, I predict, disappear as with all fads.
I feel that the landscape designer who can create sustainable, though visually interesting gardens in coastal regions are leaders in this field. Fiona Brockoff is a great example of a designer who uses indigenous plants totally suited to the harsh conditions created by salt laden winds, which according to the CSIRO are increasing in salinity. I have seen some of Fiona’s work and find it really inspiring – I love her creativity; it is so natural and in sync with the surrounding space.
Too often I see retaining walls used as a feature on a flat site. These walls are often rendered, totally at odds with sustainability because of the products used, drainage is often impeded, and imported soil needs to be brought in to fill the garden space. Have you ever done a pH test of this soil? In my region, there is not one supplier that sells soil with a pH less than 10! This is toxic to plant material, so why use it?
There are occasions when the soil that is purchased, especially ‘organic soil’, will have a pH of between 6.5 to 7.5 depending on the amount of organic matter that has been added, but this matter is added to the most inert soil that can be found. The soil too often comes from creek beds at great distance, taken to a depot where organic matter is added under high heat. The soil is then sold commercially as ‘organic’. I do stress though, that not all soil that is purchased is so badly prepared. But from my many years of landscaping experience, this is too often the case.
The extreme alkalinity can be caused by 2 possible factors – either naturally occuring limestone [calcium carbonate] in the soil or the problem is caused by salt or leaching of sodium from sodic soils, especially if sourced from inland sites. Both will affect the pH. And unfortunately this purchased soil almost always reverts to its original inert form. This is why so often plants growing in imported soil fail – it is the toxicity of the imported soil and possibly inappropriate plant selection that will not cope with the increasing alkalinity as the soil reverts, that is the problem.
There is just not enough quality topsoil to go around. If people want to buy soil, then it has to be manufactured because of the lack of supply. Why not instead, just work with the flat site? From my considerable experience, when the site is not manufactured, the garden not only looks a lot better once mature, but the garden will last long-term.
Another issue is mulch. The mulch that we used to purchase for our client’s gardens was carted great distances. I now use locally sourced council mulch – not only is it far cheaper, but it is a local product, looks great and is far better for the soil than pine bark. And don’t get me started on the hideous red and black rubbish that is sold as mulch. I can only imagine the toxins that are in the dyes used to colour the bark.
River pebbles are also a misnomer in regard to sustainability. I like the look of them like most people for a native garden, but they are too often not sustainably sourced and once again cover great distances before sale. One should question whether the removal of vast numbers of river pebbles from any water course is a sustainable action, and these are used in great quantity by some landscapers. Surely locally sourced gravels are more sustainable and they also look good.
Another thought that needs discussion here is the need to be visionary with our garden designs. Good domestic gardens should have insulating qualities that reduce the need for excessive air-conditiong. Trees have a remarkable impact here. We also need to be cognisant of the fact that in Australia in particular, our climate is changing [whether you like it or not!]. It is getting hotter and in the southern parts, drier and our gardens need to reflect these changes. So good garden design needs to be visionary. And landscapers worth their weight will bear this in mind as they design gardens for their clients.
One of the projects that we have coming up is the total replacement of a garden put in place just 3 years ago after our client’s home was completed. The garden is a disaster – totally incorrect plants were used with large surface-rooting gums too close to the home, a seeded lawn was planted in subsoil clay, garden edges were done with incorrect timbers and the design itself was substandard – and the list goes on. So these poor clients now have to pay twice for a garden that should last indefinitely if done properly.
These ideas are only the tip of the iceberg when it comes to sustainable practice with our gardens. I am not suggesting that we emulate the bush in our gardens; even I advocate some sense of design and formality – even with a native garden. I just think that the gardens being paraded today as ‘winning’ gardens are sometimes too contrived and too fad driven. And there is a sameness about many of them, which suggests that the designers have learnt design, instead of using natural design instinct to guide them. There is a wealth of difference between the finished designs.