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Taking your Garden to new heights!

Dealing with Levels in Garden Design

In a board or card game, sometimes it can feel like you have been dealt the worst possible hand and yet sometimes starting from a seeming position of disadvantage can actually see the game play into your hands; as it unfolds new opportunities arise that you did not think were possible, you get creative, you exploit and then you come out on top.  In garden design, we are sometimes dealt these difficult hands, none perhaps more so than the steeply sloping site.  Yet, with a bit of effort, ingenuity and creativity these can become the most spectacular of gardens, different from everyone else by necessitude.

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Villa Lante     Photocredit @KataPorIllustrations on Instagram

Some of the most beautiful gardens have been on steep slopes, none the more so than the extraordinary Italian villas that were developed in the renaissance period.  The two most famous examples are the Villa Lante and the extraordinary Villa d`Este. Here, sloping sites were chosen to build the gardens; it was a deliberate move in order to emphasise the levels and to position the building at the top, with the utmost vantage. Water was seen as key to the design and with a sloped site it was easier to construct the water system using gravity to feed the fountains.  Walking around the garden, moving both up and down the garden presents the garden visitor with a variety of views and vistas and an ever-changing experience.  The same premise was used at Parc Güell in Barcelona where the architect Gaudi exploited the steeply sloping site to create a variety of vistas across the cityscape.

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Terracing and steps on the slope to the front of Powerscourt House  Photocredit: Mary Bettini Blank Pixabay 

In Ireland, the terraces to the front of the house at Powercourt House and Gardens exploit the natural slope down to the river valley presenting a dramatic vista.  A central axis has been created from the house down the stone steps/terraces to the large lake below.  Here, the very fact of being on a slope means that the views over the gardens are to the landscape beyond, which is an example of a borrowed vista, in the same way as was achieved at Parc Güell.  So here is another definite advantage to being on a slope.

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Parc Güell, Barcelona – a masterpiece of landscape design    Photocredit: MariaMichelle Pixabay 

But, in order to achieve a design on a slope, there are certain technical things that must be considered.  If a designer wants to change levels or flatten them out, one either needs to cut into a slope or build up the levels with soil.  This can be done with stable soils that can easily be terraced but in most cases some form of retaining walls must be constructed in order to support the soil above.  I have been involved in all sorts of projects involving retaining walls.  I started out my career greening up engineered slopes on large-scale commercial and road engineering construction projects with slopes that had been engineered up to 60 and 70-degree angles.  These retaining systems employ the use of geotextiles and complex soil stabilisation techniques.  At a smaller scale in gardens, I have been involved in the construction of all sorts of micro-retaining walls such as blockwork wall, stones gabions and even woven willow live bioengineered solutions.

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A project using stone retaining walls designed by Tim Austen garden designs

The retaining walls in themselves can add character to a design.  If you are going for a modernist look then sleek concrete walls can be used to good effect.  For a more natural scheme a drystone wall constructed from local stone can work best.  In all cases, it is important that the drainage is also considered: naturally water will flow down a slope and it must not be impeded or allowed to back up, as this could have disastrous flooding consequences or see our retaining structures collapse.  However, as in the Italian villas this can give us opportunities to exploit water to our advantage, where we use it to create water features.

The retaining wall can include planted pockets if you are going for a greener look or you may be able to completely integrate it into the planting – it really depends on how much soil you combine with your retaining system.

I will cover the details on planting steep slopes in an up and coming blog post.

Some general advantages of creating level areas in a garden mean that you can have level beds or space for example for structures or a greenhouse.

There are costs in manipulating the ground levels, of course, and it is not necessarily the most environmentally friendly approach.  Ideally, if you can work with the original contours so much the better – work parallel to the original level contours, the less changes the better and it will be cheaper. The balance between soil cut and fill will be critical, if you can reuse the excavated soil, instead of paying for transporting it away, it will inevitably be a less expensive exercise and more environmentally friendly.  The less messing about moving soil the better really.

Furthermore, we need to build paths up our slopes.  If we introduce level changes then either long gently sloping paths are needed (and we often don’t have the space for these) or, otherwise, we need to introduce steps. Steps should be in-keeping with the overall look of the design, so the precise width and construction materials will need to be considered carefully.  I will touch more on step construction in a later blog.

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Austen house project on a steep slope

Finally, on a personal note, when I recently acquired a new piece of land on which I am lucky enough to be building a house this year for my family and developing a new garden from scratch, in some ways, I thought I had been dealt a bad hand.  Why could the perfect, flat piece of land not have been available.  Now, as the project evolves, and the design is being worked through, I am presented with so much choice as to what I cy slope.  Where will I take my inspiration from, the Italian masters or the contemporary architects, who will help me build my terraces and slopes, what can I achieve with water?  I am posting my journey on my Instagram account if you’d like to follow my decision making as the build progresses.

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Topsoil removed and levels being formed for building and walls

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