GARDENING: retaining walls can take many forms

THE need to increase soil depth is often a scenario I face in the gardens I help to develop with clients or here in our own garden at Halecat, where the natural depth of soil is hopeless, writes TOM ATTWOOD. In some cases there is little at all before bouncing off the underlying limestone. This is when some method of increasing the depth of soil is needed. Retaining walls can take many forms and range from those that are simple to the most complex constructions. The material you use will dictate the style and form of how it ultimately looks and in some cases that is less important especially when the planting will spill over the edges and hide what is there. But it may be the case that it is paramount to get the right look. For those of you who have read this column for some time now will know how much I enjoy ingenious uses of not only plants but what you can grow them in and this would also apply to retaining walls. I’m keen on gabion cages and ingenious uses of materials to fill them with but like everything there is a time and place for them. Some of the most common materials used for retaining walls are timber and often if budgets allow using a larger gauge of treated wood is always advisable. The drawback is the lifespan of the wood compared to more durable retaining walls made from stone, brick, metal or concrete. If you use timber try to use a plastic barrier to stop the soil coming into direct contact with the wood. This is less critical with the other materials, but in all scenarios, think about where excess water can escape to and drain away from. The last thing you want to create is an unintended, saturated, raised bog garden. This spring where we’d used narrow timbers to raise the depth of a border seven years ago, the tired and exhausted wood was replaced with a limestone and brick combination retaining wall. We’re really pleased with it and it should last generations.