Rock Edging Ideas: Stone Borders That Last

Rock edging gives a bed or path a natural, long-lasting frame that only gets better with age. Cobbles, slate, flint, pebbles and local stone all work. The secret is the base underneath: set the stones properly and they’ll stay put for decades.

This guide covers which stone to choose, how to lay it, and eight style ideas with plants that soften the edge. If you’re still choosing between materials, the guide to garden edging ideas compares stone with sleepers, brick, steel and concrete. For cutting and keeping a crisp grass edge, see the lawn edging guide.

Which stone is best for garden edging?

Choose stone that suits your house and the look you want. Local stone usually looks most at home and is often cheaper, because it hasn’t travelled far.

Colour matters as much as shape. Honey limestone suits warm Cotswold-style stone. Blue-grey slate gives a cool modern line. Grey cobbles are soft enough for almost any garden. Buy a sample bag first and hold it against your house and paving.

Butt cobbles tight in a single row and let plants flop over the top to blur the join.

How to lay rock edging so it lasts

The base makes or breaks a stone edge. Without one, stones sink, tilt and fill with weeds within a season. There are two ways to do it, depending on whether you mow up to the edge.

Dry-laid edging

Dry-laying suits cobbles, pebbles and irregular rockery stone.

1. Dig a shallow trench, about 5-8cm deep, along the bed line.
2. Firm the base with a hand tamper or the back of a spade.
3. Lay a weed membrane in the trench and up the bed side.
4. Add a few centimetres of sharp sand or fine grit.
5. Set the stones tight together and tap each one level.
6. Backfill behind with soil or gravel so nothing rolls out.

It’s cheap, quick and easy to change later, but needs a quick weed now and then.

Mortar-bedded edging

Mortar-bedding suits slate on edge, setts and any edge you mow over. Dig down about 10cm, lay a firm, compacted base of hardcore (MOT Type 1) or sharp sand, then bed the stones in a 1:4 mix of cement and sharp sand. Point the joints once it’s set. Mortar locks every stone in place, so frost and mower knocks can’t shift them.

For big rocks and boulders, sink about a third of each one into the ground. A boulder sitting on top looks dumped. Sink it a little and it looks as if it’s always been there.

Warning: Don’t set stone straight onto bare clay. Clay swells, shrinks and heaves in frost, and unbedded stones will tilt within a winter. Always dig down, compact a base and bed the stones in sand or mortar.

Slate set on edge in mortar gives the sharpest line of any stone, and suits modern gardens.

Eight rock edging ideas with planting

The best stone edge does two jobs: it holds the line, and it carries plants that soften it.

Cottage-garden cobble edge

A single row of rounded cobbles is the friendliest edge there is. Plant hardy geraniums, lady’s mantle and catmint to spill over the stones and hide the gaps. The cobbles hold the mulch in, and the plants do the rest.

Coastal pebble border

Smooth grey and buff pebbles give a beach feel, especially near the sea or around gravel. Lay them in a wide band rather than a single row. Plant sea thrift, sea holly and fine grasses such as Stipa tenuissima. It pairs well with a gravel garden.

Alpine scree edge

Pile small rockery stone into a low, gritty edge and tuck plants into the gaps. Plant creeping thyme, houseleeks and aubrieta to root between the stones. It makes a lovely lip for a rockery.

Creeping thyme and houseleeks rooting between the stones. The plants shade out weeds and soften the edge by midsummer.

Modern slate line

Set slate upright in a continuous mortared line for a clean, contemporary look. Keep the planting simple, with clipped evergreen balls, low grasses or euphorbias. It suits courtyard and city gardens.

Low gabion edge

A shallow steel cage filled with angular stone makes a raised edge that also holds back soil. It suits modern and sloping gardens. Let trailing rosemary or aubrieta tumble over the top to soften the cage. Gabions also make a strong frame for raised beds.

A low gabion edge holds back soil and never needs repointing. Trailing rosemary softens the steel.

Flint border

Whole or knapped flint gives a knobbly edge that suits chalky areas and older houses. Bed it in mortar so the nodules don’t roll. Its grey and white faces look good with lavender, nepeta and old roses. Flint is very hard and barely weathers.

Mortared flint suits older houses and chalky areas, and looks good with lavender and roses.

Dry stone mini-kerb

A low, two-layer dry stone kerb makes a smart raised edge for a sloping border. Use flat local sandstone or limestone. Let Mexican fleabane (erigeron) seed into the joints, just as it does on old walls.

Path edge with setts and pebbles

Edge a path with flat setts set level with the surface, then fill the bed side with pebbles. It stops gravel wandering into the border. See garden path ideas for more layouts.

Flat setts keep the gravel on the path, and a band of pebbles makes a tidy strip in front of the plants.

Is rock edging good for wildlife?

Yes, dry-laid stone is one of the most wildlife-friendly edges you can choose. The gaps between the stones shelter ground beetles, which eat slugs and their eggs. In damp borders you might find the odd frog or toad sheltering there too. Mortared stone, metal and plastic offer far less shelter.

Plants to soften a stone edge

A bare stone edge can look raw for the first season. Plants fix that. Low, spreading plants knit the stone into the bed and shade out weeds in the gaps.

For a sunny edge, rock roses sprawl happily over warm stone and flower for weeks. The guide to growing cistus rock rose covers the best varieties. Thyme, aubrieta, erigeron and dwarf hardy geraniums do the same job in different colours. Plant them on the bed side, about 20-30cm back from the stones, and let them creep forward.

Common rock edging mistakes

• Loose stones near the lawn. Cobbles that sit proud get knocked into the mower. Set them low or mortar-bed any edge you mow over.
• No membrane. Weeds grow up between loose stones within a year. Lay membrane before you set a single rock.
• Wrong scale. Tiny pebbles vanish against a big border, and boulders too big to mow round trap long grass. Most borders suit stones of about 10-20cm.
• No proper base. Stones dropped onto soft soil sink and tilt. Always compact a base and bed them in sand or mortar.
• Too many stone types. Three stones in one edge looks accidental. Stick to one stone and one size for each run.

Now you’ve planned your stone edge, read the guide to railway sleeper edging if you’d like a chunkier, raised frame for your beds. For more ideas, browse our garden design guides.

Frequently asked questions

How much does rock edging cost?

It depends on the stone and how you lay it. Dry-laid cobbles or local stone are usually cheapest. Mortar-bedded edging costs more because of the base and cement. Slate, flint, granite setts and reclaimed stone tend to be dearer. Local stone is often cheaper because there’s less haulage.

Do I need a membrane under stone edging?

Yes, under loose stone edging it’s worth it. A weed membrane stops grass and weeds growing up between the stones. Fold it up the bed side, pin it and cover it so it’s hidden. Mortar-bedded edging doesn’t need one, as the mortar fills the gaps.

How deep should I bury rocks used for edging?

Bury larger rocks by about a third of their height. That anchors them against knocks and frost and makes them look settled. Set smaller cobbles in a shallow trench on a firm, compacted base. Keep the tops low if a mower wheel needs to run over them.

Is rock edging better than timber or plastic?

It lasts much longer, but costs more to start with. Stone doesn’t rot like timber or go brittle in sunlight like plastic. Dry-laid stone needs a little weeding, and the gaps shelter beetles and other small creatures. For a thin, crisp line, metal edging is neater.

What stone is cheapest for garden edging?

Bulk bags of cobbles or local quarried stone are usually the cheapest. Reclaimed stone, granite setts and big rockery boulders cost the most. Buy a sample bag first to check the colour against your house and paving.

Can you mow over stone edging?

Yes, if it’s mortar-bedded flush with the lawn. Set flat setts or slabs level with, or just below, the grass so the mower wheel runs over them. Loose cobbles that sit proud can be flung by the blade and damage the mower.