Key Takeaways
- A small rockery looks right when the bands in every stone run in one direction, level with the ground, and a third to a half of each large stone is buried. Stones just sat on the surface, each facing its own way, are what make a rockery look unnatural.
- Two or three large stones beat a dozen small ones in a small rockery. A lead stone flanked by two smaller ones of the same type reads as an outcrop, and planting fills the space between groups better than more stone does.
- A membrane under a small rockery does not stop weeds. Fabric separates a rubble drainage layer from the soil above it, which is a different job, and weeds germinate in the debris that lands on top of it regardless.
- Rockery stone is priced by the tonne, and a small rockery needs roughly 5 to 15 large pieces rather than a bulk load. A rockery being dismantled nearby, or a local quarry, is often the cheaper way to get that quantity.
- A weed-choked small rockery is fixed with more planting, not more rock. Dense mat-forming plants keep light off germinating seed, which a layer of stone on its own never manages.
I remember a customer once standing beside a newly built rockery of his own and his wife, wryly asking me, why it looked like a pile of rocks dumped on the soil. I had to admit, looking at it, that it was a fair question. The stones were all much the same size, each one sitting on the surface facing a different way, with little alpines tucked into the gaps and a membrane underneath because that was what he’d seen recommended. It reminded me more of a load of stone that had been delivered and never properly unpacked than a rockery, and I remember thinking that the problem wasn’t really the plants at all, it was the way the rocks had been placed.
The good news is that a small rockery is easier to get right than a big one, because you can afford to be fussy about three or four stones. The 16 ideas below are the styles I built, followed by the four things that decide whether they work.
Why Does My Rockery Look Like a Pile of Rocks?
A rockery looks like a pile of rocks when the stones sit on top of the soil, face different directions, and are all roughly the same size. Fix those three and the same stones look like they were always there.
- Bury the base. A third to a half of the height of every large stone goes under the soil, firmed in so it does not rock.
- Run the layers the same way. Most rockery stone has visible strata (the bands the rock formed in). Set every piece so those bands run level and in the same direction across the whole rockery, like one outcrop broken up. A lot of guides say to face rocks different ways for interest. In my opinion that is exactly what makes a heap.
- Group, do not scatter. A lead stone, two smaller ones of the same type beside it, then a gap, then the next group. Odd numbers, varied sizes, and never an even row.
Bigger reads better, too. Three big stones beat ten middling ones.
16 Small Rockery Ideas
1. Three stones where the lawn meets the border
In a small garden this is often the only spot going, and the mower runs right past it. Set the stones back from the cut edge and fill the gap with a low tumble of pebbles and some Blue fescue (Festuca glauca), so the stone starts small and grows into the group. It keeps the mower blade off a buried edge too, which I have found the hard way.
2. The buried giant
Set one flat stone so low that only the top few centimetres clear the soil. The eye finishes the job and fills in something enormous underneath. It is the cheapest trick in the book. Place it a little apart from the main group, with Mountain avens (Dryas octopetala) creeping over one edge.
3. A ledge rockery on a short bank
A bank of a metre or so takes a ledge rockery: two or three shallow shelves of flat stone, each one starting with the heaviest piece you can lift, because that is what stops the rest walking downhill. The capstones decide how it looks. Tip them back into the bank rather than forward like a step. Rain then feeds the planting behind each shelf instead of running off the front and washing out the one below.
4. A split-slab outcrop on flat ground
Pick a stone that splits along its own lines, sandstone or limestone rather than granite, and lay the pieces as though one slab cracked apart where it sat. Keep the gaps to a few centimetres and push young saxifrages and Erinus alpinus (Fairy foxglove) into them. On a flat lawn this is the layout that looks least like something you bought.
5. A rubble mound for a flat garden
Flat garden, no bank, heavy soil: build the height yourself. Take out the top 15 to 20cm and backfill with broken brick or coarse gravel. Lay turves upside down over that, or a permeable fabric, so the soil above cannot silt it up. Then mound your gritty mix on top. That fabric is doing separation, not weed control.
6. A crevice bed
A crevice bed is flat stones set on edge, nearly touching, the thin gaps between them filled with a gritty mix. Plants root down into cool, deep slots rather than sideways into warm soil, which suits the choosy alpines that rot off in a normal bed. Poke in small, young plants; big rootballs will not go.
7. A dug-out hollow in front of the mound
Before you build up, dig down. Scoop a shallow dip in front of the rockery and floor it with rounded cobbles. Dropping the foreground is what makes the stone behind look twice the size. A dry water run curving round the mound finishes it.
8. A north-facing shade rockery
Four hours of direct sun or less and you have a shade rockery, so treat it as one. Spleenwort ferns (Asplenium), Ramonda myconi tucked into a north-facing crevice, and hardy cyclamen planted in the green in late winter are all happier there than anything wanting a mountainside. The plants change, not the placing.
9. A two-metre Japanese dry garden
Two metres square is enough. Three stones set as islands, each placed upright or flat according to its own shape, and 25 to 40mm gravel raked around them to stand in for water. One dwarf mountain pine (Pinus mugo) if you want a plant at all. Resist the fourth stone.
10. Stones flanking garden steps
Where steps already cut through a slope, set a rockery either side of them rather than building one somewhere new. Irregular or arching stones beside steps suggest movement; one upright piece at the top gives height.
11. A boulder group by the front door
In a small garden this is often the only spot going, and the mower runs right past it. Set the stones back from the cut edge and fill the gap with a low tumble of pebbles and some Blue fescue (Festuca glauca), so the stone starts small and grows into the group. It keeps the mower blade off a buried edge too, which I have found the hard way.
12. A planted dry-stone wall top
The top of a dry-stone wall is a rockery you already own. Fill the gaps along the top and the face with gritty soil and plant Stonecress (Aethionema grandiflorum), Rock cress (Arabis) to cascade down the face, and sedums in the dips. Shear the arabis back by half after flowering.
13. A herb rockery you can cook from
A sunny small rockery is a natural herb bed. Let thyme run out across the grit, add oregano, one lavender and a sage. The grit that keeps an alpine’s neck dry does the same for Mediterranean herbs, which is why they last longer here than in a border.
14. A winter-and-spring bulb rockery
Most small rockeries peak in May and sulk from July. Plant for the other end of the year: Iris reticulata and the dainty daffodil ‘Tête-à -Tête’, Cyclamen coum, crocus and snowdrops in the pockets between stones, with sempervivums and sedums holding it together. Leave the daffodil foliage to die back on its own.
15. A coastal rockery
Sea thrift (Armeria maritima) grows wild on sea cliffs, so a rockery in full sun on sharp drainage is home to it. Pair it with Blue fescue and a Rock rose (Helianthemum) for early summer. Thrift gets a little compost and almost no water; it is killed by kindness.
16. A reclaimed-stone rockery for next to nothing
The best small rockery stone I ever placed was second-hand. A rockery someone is dismantling, a builder’s excavation pile, a local quarry: all three sell or give away odd pieces a garden centre would price singly. Weathered stone with moss and lichen on it is what you would otherwise wait ten years for. Anything that flakes away in your hands goes back on the pile.
Do You Need a Membrane Under a Small Rockery?
A small rockery does not need a membrane, and a sheet under the whole thing usually makes it worse. I know that is not what most guides say, and I sell the stuff. Fabric does four jobs people run together, and it only does one of them properly.
| Job | Does a membrane do it? | What to do instead |
|---|---|---|
| Keeping a rubble drainage base from silting up with the soil above it | Permanently, and this is the one place I use it | Nothing else needed |
| Blocking weeds rooting up from below | For a few years, then roots find the overlaps and the pin holes | Dig every perennial weed out by the root before a stone goes down |
| Stopping seed germinating in the debris that lands on top | No, in any weight or weave | Dense mat-forming planting, and a rake through the grit each spring |
| Holding a mound of soil and stone on a bank | No, it makes it worse, because the load slides on the sheet | Strip the turf and the seed-bearing topsoil, work in sharp sand or grit, build onto that |
Where fabric does earn its keep, and the weights worth paying for, is covered in what to put under gravel.
How Many Rocks Do You Need for a Small Rockery?
Yards sell rockery stone by weight, and that does not change if you only want four pieces. Rockery boulders start at around 45kg each, so a small order gets heavy faster than people expect. Here is how the quantity breaks down.
| What it is | What it does in a small rockery | How it gets moved |
|---|---|---|
| Lead stones, 350mm and up | Anchors a group. One per group, and it sets the height and the line everything else follows | Three people, two moving and one standing clear calling the placement. Past about 45kg it is a delivery-service job to get it near the site |
| Companion stones, 200 to 350mm | Echo the lead and settle it into the ground. Where most of your order goes | One person for most of them. Anything over 25kg goes on a wide-tyred trolley over planks, never a wheelbarrow |
| Small infill stones, under 200mm | Bed and steady the larger pieces. Mostly buried, and not there to be looked at | By hand |
| Washed horticultural grit as a dressing | Finishes the surface between plants, about 1cm deep and taken in tight around each crown | Bagged |
Stick to a single stone in a spread of sizes, and check the lorry can get near enough that you are not barrowing it round the house. If anyone is digging near you, ask what they are turning up. We may be able to put together rockery pieces to order, so if a bulk bag is more than you need, get in contact for a price on a smaller quantity. How big stone is sold, and how to buy a handful of pieces without taking a lorry load, is in rocks in landscaping.
How Do You Stop a Small Rockery Filling With Weeds?
The way to stop a small rockery filling with weeds is to plant it densely enough that mat-formers cover the soil between the stones. A rockery is low-maintenance once the plants have closed over, not because it has rock in it.
Dig out every perennial weed by the root before a stone goes down, because no mulch or sheet controls an established perennial. Then plant more than feels sensible: thyme, Campanula carpatica, Dryas, the smaller sedums, with about 1cm of washed horticultural grit up to their necks. For the first two years, hoe and rake the gravel between them regularly. It dislodges seedlings and it looks sharp. Aubrieta wants a hard prune each year, or it turns into a woody mat that lets the weeds in.
If you have inherited a rockery that is more weed than plant, the fix is fewer stones and more plants. I never once made a rockery tidier by adding rock to it.
Next Steps
We stock decorative stone and slate chippings for dressing the ground between the stones, and weed fabric for the one job it does in a rockery, which is separating a drainage layer. For the stone itself, get in contact and we will price a small quantity. The build itself is covered step by step in how to build a rockery, the planting in rockery plants, and if slate is the stone you are after, slate rockery ideas covers the colours.
If you would rather talk your rockery through with a person, ring Outdoor Aggregates on 0330 043 7585. The office is open 7am to 7pm, seven days a week.
Have you ever built a small rockery? How many stones did you end up with, and did any of them go back out again? Let us know in the comments.
FAQs
What is the best stone for a small rockery?
The best stone for a small rockery is one local type in three or four sizes, weathered rather than fresh-cut, and angular rather than rounded. Steer clear of crumbly mica-rich rock, which weathers badly.
How long after building should you wait before planting a rockery?
Leave about two weeks between building and planting a small rockery, so the stone and soil settle and you can top up the cracks and low spots that open up. If it has not rained in that time, run a sprinkler over it for a few hours rather than waiting on the weather.
Do rockery plants need special soil?
Rockery plants need a gritty, sharp-draining mix rather than ordinary garden soil. Work horticultural grit and washed sand into heavy ground, or for a container mix John Innes No.2 half and half with clean grit, and vary it pocket by pocket for what each plant wants.
Where can you get cheap or free rocks for a small rockery?
Facebook Marketplace is the best source of cheap or free rockery stone, because people pulling out an old rockery usually want it gone rather than sold. Local quarries are the other call worth making, since they will often let you have odd pieces when an online garden retailer only sells packs. Anything already on your own plot, from a dug-out footing or a wall that has come down, has cost you nothing at all.
How do you make a small rockery look bigger than it is?
A small rockery looks bigger when you lower the ground in front of it instead of building it higher. A shallow scoop at the front, floored with cobbles, plus one big stone sunk so deep that barely anything shows, and the eye supplies depth that is not there. Put height behind it, an evergreen or a small shrub, and the illusion holds.