Why a Dry Stone Wall Belongs in a Smallholding Garden

A dry stone wall is one of the most useful things you can build on a smallholding. It costs nothing but time and whatever stone you can scrounge, it lasts for decades, and it does three jobs at once: it holds a border in place on sloping ground, it gives you a warm, free-draining microclimate for herbs and alpines, and it provides a home for the sort of wildlife that eats aphids. Toads, slow worms, beetles and solitary bees all shelter in the gaps. A mortared wall gives them nothing.

The technique is old and simple. You stack stones so that each one rests firmly on the two below it, with the wall leaning slightly into the bank it retains. No cement, no pins, no fuss. What follows is the method I use for low garden borders, roughly 40–60cm high, which is the size that suits most plots and most backs.

Choosing the Right Stone

Almost any stone will do, but some are far kinder to work with than others. You want stone with at least two reasonably flat faces and a shape that is wider than it is tall. Sandstone, limestone, granite field clearance and slate waste all work well. Rounded river cobbles are the exception: they have no grip, and a wall built from them will slump within a season unless you are very skilled.

If you are buying in, order by the tonne from a local quarry or reclaim yard and ask for walling stone rather than decorative rockery stone. Rockery stone is priced by the piece and will bankrupt you. Roughly one tonne builds about two square metres of face at this height, so a 6m border needs three tonnes. That sounds a lot until you see it in a heap.

• Face stones: the long, flat-ish stones that make the visible sides.
• Through stones: long stones that span the full width every metre or so, tying the two faces together.
• Hearting: the small chips and wedges that fill the middle and stop everything shifting.
• Coping: the top row, set on edge or as heavy flat stones.

Sorting and Setting Out

Tip your stone onto a tarpaulin or a firm piece of ground and sort it before you lay a single one. Make three or four piles: large flat faces, medium building stone, small hearting, and coping. This takes an hour and saves you three. Nothing is more miserable than hunting through a heap for a wedge while balancing a 20kg stone on your knee.

Next, dig a shallow foundation trench about 15cm deep and slightly wider than the wall. On soft ground, fill it with compacted rubble or scalpings. Dry stone walls fail at the base far more often than anywhere else. Set your first course of large stones flat in this trench, bedding them down with a mallet so they cannot rock. Run a line between two pegs at either end and keep the base about 45–50cm wide for a 55cm-high wall. The wall tapers as it rises; the faces should lean inwards at roughly one in ten.

The Rules of Placing Each Stone

Work from both ends towards the middle, or along one face and then the other, but always keep the courses level. Every stone must sit on at least two points of contact, and it must never rock. If it rocks, lift it and try again, or bed it on a small wedge of hearting. Do not be tempted to force it.

• One over two, two over one. Never let a vertical joint line up with the joint below it. Stagger them like brickwork.
• Long side into the wall. A stone should show its narrowest face to the world and bury its length in the middle.
• Pack the hearting as you go. Every gap behind the face stones gets a chip tapped in. This is what makes the wall rigid.
• Batter the faces inwards. Keep checking with a plumb line or a spirit level held against the batter board.
• Tie it with through stones. Place one every 1–1.5m along the wall, at roughly half height and again near the top.

Coping and Finishing

The top is where a garden wall looks after itself or looks a mess. Traditional coping stones are set on edge, leaning slightly into the bank, packed tight against their neighbours, and often topped with a heavier "boulder" stone every few metres. If you do not have proper coping, a single row of heavy flat stones laid across the full width of the wall works perfectly well and is much quicker.

Whichever you choose, the coping must overhang the faces slightly so rain drips clear of the joints rather than running down into the wall. Fill the top with hearting and tap everything home. Stand back and check the line; a wall that looks straight to the eye is straight enough.

Planting Up and Aftercare

Leave the wall for a week or two before you lean on it or plant against it, so it settles into its own weight. Then the fun begins. The sun-warmed face is ideal for thyme, marjoram, alpine strawberries, aubrieta, campanula and houseleeks. Tuck small plants into the gaps between stones, adding a pinch of compost behind the roots.

Keep the base clear of ivy and bramble, which will prise the wall apart over time. Check for movement after the first winter and re-wedge any loose stones while the job is still small. Do that, and a well-built border wall will outlast you, quietly doing its job and housing a surprising amount of wildlife in the meantime.