Dead flat gardens are surprisingly rare. Where different levels must be retained, some forethought can make a big difference.
1) Timber remains the most common choice, probably based on price and the DIY ethos. It is holding back a considerable weight of soil that will be wet and exerting outward pressure, so strong construction is critical. Walk around established suburbs and you are sure to find older timber retaining walls bulging outwards. You need to get the supports right, both horizontally and vertically, to keep it all in place. Milled timber must be tanalised to ground retention grade or it will rot quickly.
2) A cut stone wall is permanent, aesthetically pleasing and probably the most expensive option. The part-time stonemason here critiques my photos of modern stonework, pointing out that the stones should be keyed in to each other (as brickwork is). You should not be able to pick out vertical lines running down the wall because these are a point of weakness which indicate that it is the mortar holding the stones together. I mention this in case you decide to commission a stone wall of your own.
3) Immediately next door to the attractive stone wall is the DIY option – although probably involving some lifting machinery to get the rocks in place. These have cement laid between them, which is unlikely to be structural but merely to keep out weed growth. Keen gardeners might prefer to plant between the rocks. Interestingly, some gradient has been left here rather than the vertical cut seen on the adjacent stone wall. Allowing a gradient reduces the outward pressure the retained ground will exert.
4) Further down the same street, I found the true DIY option. Smaller stones, able to be lifted by one or two people, have been placed and the area has been turned into a rockery on a sloped gradient again. Once established, plant roots will hold a certain amount of soil in place. The owner of this frontage is clearly a keen gardener.
5) Ugly functionalism at its worst – and I can say that because this is on a property we bought. Concrete blocks have been used to retain the straight sections, poured concrete on the curves. It does the job. That is all there is to say. If I still lived in that house, I would be contemplating plastering and painting the retaining walls to try and make them a little less brutal.
6) Faced with a similar situation to the preceding photo, this example shows what a little more thought, imagination and money can achieve. These are blocks – though whether a soft stone or aggregate, I am not sure – but a much superior look in aesthetic terms with the softer edges and random sizes. What also makes a big difference here is the flat capping on the top of the retained sections. It is a stylish finishing touch.
7) The same bottom layer of retaining wall has been used throughout this modern subdivision. This house shows a mix of materials used in the quest for privacy, ground retention and street appeal. It was so well executed that I suspect a professional was employed to achieve this effect. The usual advice is not to mix materials but you can see the use of cobblestone bricks, timber, hedging and a relatively wide palette of plants. Prostrate plants are being used to retain the sloping bank.

First published in the Waikato Times and reprinted here with their permission.