Why a dry stone wall earns its place by the sea

Coastal gardens face salt-laden winds, driving rain, and thin, free-draining soil. A dry stone wall, built without mortar, creates a sheltered microclimate. The gaps between stones let wind pass through rather than batter a solid barrier, reducing turbulence. The stone's mass absorbs warmth by day and releases it slowly at night, offering frost protection for tender plants.

It is also a wildlife haven. Insects, spiders, and small mammals shelter in the crevices, whilst lichens and mosses colonise the surface. For coastal gardeners, it ties the plot to the local landscape — a traditional feature among dunes, cliffs, and windswept fields.

Choosing the right stone for a salty climate

Choose a locally quarried stone that has proven durable in coastal conditions. Sandstone, limestone, and granite work well; avoid soft, flaky stones that crumble after salt spray and frost. If local stone is unavailable, ask a quarry for a frost-resistant, salt-tolerant grade.

• Sandstone: Often flat and rectangular. Check frost resistance.
• Limestone: Durable and traditional, though some types are porous.
• Granite: Extremely hard-wearing but heavy. Best for foundations and through stones.

Aim for a mix of sizes: large face stones, smaller hearting, and a few long through stones. You need roughly one tonne per square metre of wall face.

Preparing the ground and laying a firm base

A dry stone wall is only as good as its foundation. On sandy or rocky coastal ground, dig a trench about 30 centimetres deep and slightly wider than the wall. Fill it with compacted hardcore or large, flat stones.

Use a spirit level and string line to keep the wall straight. On a slope, step the foundation down in level sections rather than following the gradient. Angle the wall slightly into the prevailing wind — a batter of about 1 in 10 adds strength and sheds water.

Building techniques: hearting, through stones and coping

Start with the largest, flattest stones at the base. Build both faces at the same time, keeping them level. Fill the centre with smaller hearting stones — these lock the faces together and prevent movement.

Every metre or so, place a through stone spanning the full width. These tie the structure together. Aim for a wall 50 centimetres thick at the base, tapering to 30 centimetres at the top. This batter, with through stones, lets the wall flex in strong winds without collapsing.

Finish with a coping — stones placed on edge or at an angle. This caps the wall, sheds rain, and shelters insects. On exposed sites, use heavier coping and consider a double layer for extra weight.

Encouraging wildlife in the gaps

The crevices between stones shelter overwintering insects, solitary bees, and small mammals like shrews. To make your wall more attractive to wildlife:

• Leave some gaps un-mortared and avoid filling every space with hearting.
• Plant drought-tolerant, salt-resistant species at the base, such as sea thrift or wild thyme.
• Allow mosses and lichens to grow — they feed invertebrates.
• Position a few stones slightly proud to create basking ledges for lizards or insects.

Do not tidy the wall too much. A little untidiness is exactly what wildlife needs.

Looking after your wall in a salty climate

Dry stone walls are low-maintenance, but coastal conditions take their toll. After winter storms, check for dislodged stones or slumped sections. Repair promptly by rebuilding the affected area — do not just push stones back, as this weakens the structure. Check the coping after gales, too.

Avoid weedkillers or pressure washers, which damage stones and destroy habitats. Pull woody weeds by hand, and trim overhanging plants in late winter. If salt spray is severe, a gentle rinse with fresh water after a storm can help.

With a little care, a dry stone wall will last for generations, providing shelter for plants, a home for wildlife, and a timeless feature for any seaside garden.