Dry Stone Walls and Raised Beds

Field boundaries marked by stone walls are a common landsc in the country. A close inspection will reveal that these walls colonised by plant communities, flourishing in the perfect drainage and shelter the stone fabric provides.

These walls can be translated to the garden and used to create low terraces against boundary walls or freestanding raised beds in the garden. Raised beds are usually rectangular, although it is possible to build them in curved shapes.

You can use real stone to make the walls, or you can purchase reconstituted stone, which is available in a variety of colours and shapes. This is cheaper than real stone and also easier to use since the blocks are more uniform in shape and size.

If the wall is to be taller than 30 cm/12 in, you must make a sound foundation by digging a trench around the perimeter as wide as the width of the wall and about 15 cm/6 in deep. Fill the trench with 5 cm/2 in of rubble, which you must ram down well into the bottom of the trench, and then cover this with concrete. When the concrete is set, lay the first course of stones and cement them to the foundation.

As you progress with each course, lay the stones so the wall slopes inwards slightly. Do not make the walls of a raised bed any taller than 1 m/3 ft tall; a run of dry stone wall for a terrace or retaining wall can be up to 1.2 m/4 ft tall. The finished width of a raised bed should be only about 1.5-1.8 m/5-6 ft, so that the centre can be easily reached from any side.

Part of the attraction of a stone wall is the planting, which can be done between the stones, so that you can have cascades of aubrietia, sprays of sedum and so on. It is very important to remember that any planting must be done while the wall is being made. Once the stones are in place it will not be possible to successfully introduce a plant’s roots between the stones. So plant as you go, firming soil around the roots and between the stones.

When the raised bed is complete, fill it one-third full with clean rubble over which you then spread a layer of free-draining compost. Leave this to settle before planting, after which you finish off by spreading a 2.5 cm/1 in thick mulch of clean gravel.

The finishing touch is to make an apron of gravel around the base of the bed or along the wall footing. This will prevent the raised stonework looking like it was dropped by accident onto the lawn. The gravel border also makes it easier to trim the lawn edge, prevents grass growing into the stones and generally makes for a neater appearance.

The apron should be 25-30 cm/ 10-12 in wide and the gravel layer about 7.5 cm/3 in deep. If you lay a ribbon of horticultural fabric mulch under the gravel it will help to suppress weed growth.

26. February 2012 by Dave Pinkney
Categories: Alpines, Featured Articles, Plants & Trees, Rockery Garden | Tags: , , , | Comments Off on Dry Stone Walls and Raised Beds


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