Decorative aggregates do quiet, unglamorous work in a garden, and they do it better than almost any other surface. A loose stone covering suppresses weeds, sheds rainwater, hides bare soil through winter, and finishes a path or border with colour and texture. It needs no mowing, no feeding and no repainting. It also happens to be one of the cheapest ways to make a scruffy corner look deliberate.

This guide covers what to choose, how deep to lay it, and how to keep it looking sharp for years rather than one season.

Choosing By Size And Shape

Size matters more than colour when you are deciding where a stone will actually work. Rounded stones roll; angular stones lock together. Get that wrong and a path becomes tiresome to walk on.

• 4–10mm pea shingle. Rounded and pale, ideal as a mulch around alpines, herbs and gravel-garden planting. It rolls underfoot, so avoid it on slopes and on paths where you push a barrow or wheelie bin.
• 10–14mm pea gravel or angular chips. The general-purpose choice. Good for borders, seating areas and light foot traffic.
• 14–20mm angular gravel. This is the workhorse for paths and driveways. The jagged edges interlock, so it stays put on a gentle slope and forms a firm, quiet surface.
• 20–40mm chippings, cobbles and paddlestones. Bigger, bolder and best used as a feature — a band of Scottish cobbles beside a step, or large slate chippings across a wide border where you want impact from the kitchen window.
• 6–10mm horticultural grit. Not a surface at all, but invaluable as a top dressing around alpines and sempervivums to keep damp off the crowns.

A Quick Tour Of The Popular Stones

Pea shingle is the classic pale cream and grey mix, neutral enough to sit with almost any planting. Cotswold buff is a warm honey limestone that lifts shady borders and looks superb with purple sage and lavender. Granite chippings come in silver-grey and a pinkish hue, hard-wearing and slow to fade.

Slate is the dramatic option: flat, angular flakes in plum, green or blue-grey that deepen in colour when wet. It is heavier per bag than gravel and settles into a wonderfully crisp finish, though it can be sharp under bare feet. Flint brings a soft, honeyed brown with white fracture marks, and Scottish cobbles give rounded, sea-worn forms for focal points.

One caution: brightly coloured dyed aggregates often fade to a washed-out pink within a couple of summers. Natural stone costs a little more and keeps its character.

Depth, Sub-Base And Edging

A decorative layer is only as good as what sits beneath it. For a path or driveway, excavate to about 150mm, lay a compacted sub-base of MOT Type 1 stone to roughly 100mm in two layers, then add the decorative aggregate on top.

• Allow 40–50mm of loose stone for 10–20mm grades.
• Allow 60–75mm for 20–40mm chippings.
• For a border mulch, 50mm is plenty, laid straight onto a woven geotextile membrane.

One bulk bag of around 850kg covers roughly 10–12 square metres at 50mm, so measure before you order and add a little for settlement.

Edging is what stops the stone wandering into the lawn. Steel edging is discreet, timber is inexpensive, and a soldier course of brick set on mortar looks traditional. Set the top of the edging about 25mm proud of the finished surface.

Aggregates, Plants And Drainage

Stone is inert, but it is not always neutral. Limestone and chalk-based chippings raise soil pH over time, so keep them away from rhododendrons, camellias, pieris and blueberries, which all prefer acid ground. Slate, granite and flint are safe around everything.

When mulching borders, leave a clear collar of 5–10cm around the stems of shrubs and perennials. Piling stone against bark traps moisture and invites rot. And remember that gravel is no barrier to a determined weed — it simply makes the ones that germinate easy to pull out.

For drainage, clean 20–40mm stone is what you want, with the fines washed out. A French drain filled with this grade will carry water away far better than shingle, which compacts and clogs. The same stone wrapped in a permeable membrane makes a neat, invisible soakaway beneath a border.

Keeping It Looking Its Best

Loose aggregate is low maintenance, not no maintenance. Once a year, rake the surface to redistribute stone away from traffic lanes and back towards the edges, then top up any thin patches rather than replacing the lot.

• Blow or rake off fallen leaves and grass clippings. Organic debris silts up the gaps and gives weed seeds somewhere to root.
• Pull weeds young, while they lift out with a twist.
• Rinse slate and darker stones with a hose to refresh the colour; a light pressure wash once every few years is plenty.
• Check edging each spring and firm any sections that have shifted.

Choose the right grade for the job, prepare the ground properly, and a decorative aggregate surface will earn its place for fifteen years or more — quietly doing the work while you enjoy the planting around it.