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How to lay ornamental gravel

Updated: October 2026

You have a stack of 20 kg sacks and a strip of soil that should become a path, a border mulch, or a planted gravel patch. This page is how to lay ornamental gravel from courier bags: choose a depth, count the sacks, and decide whether a membrane helps or gets in the way. It does not rank the twelve ASINs. Rounded pea still needs an edge, and a membrane is a different choice on a path and under planting. Prices stay on the [ornamental gravel comparison](/hub/fertiliser-soil-and-bark-mulch/ornamental-gravel).

You have a stack of 20 kg sacks and a strip of soil that should become a path, a border mulch, or a planted gravel patch.

Our top picks

Amtra Amtra Polychrome 5 kg

Best overall

Amtra Amtra Polychrome 5 kg
8.6/10about £4.88
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Hisredsun Hisredsun white stones 1.8 kg

Alternative

Hisredsun Hisredsun white stones 1.8 kg
8.1/10about £10.99
View offer
Westland Westland garden gravel 20 kg

Rank 3

Westland Westland garden gravel 20 kg
8.9/10about £11.00
View offer
On this page
  1. 1.Planted bed versus a path you walk
  2. 2.Depth and how many 20 kg bags
  3. 3.Membrane, edging, and sub-base
  4. 4.Rinse, dust, and topping up

Planted bed versus a path you walk

A planted gravel garden sits on prepared soil. Gardens Illustrated talks about 5–7 cm. Beth Chatto’s notes use about 3–5 cm, and at least 25 mm, of local 10 mm gravel. Those pages argue against a membrane under planting, because fabric blocks seedlings. A path needs an edge and a firm base: excavation, timber edging, a fabric separator, compacted MOT Type 1, then the decorative layer. Wickes writes about 25 mm of gravel below the edging. Merchant tables more often want 35–50 mm. Westland’s own how-to says 2–5 cm on a path and 2–4 cm as rockery mulch. Those figures are guidance. Rounded pea migrates without an edge. The RHS finds angular medium grades easier to walk on, and this set does not sell that stone. Job and grade sit on the ornamental gravel buying guide. Do not use this sequence for a drive. Front-garden rules sit on ornamental gravel driveway planning.

Depth and how many 20 kg bags

Beesley & Fildes say a 20 kg bag covers about 0.25 m² at 50 mm, or about 0.4 m² at 30 mm. The RHS says a 25 kg bag covers about 0.6 m² at 5 cm. Those are different density assumptions. Westland is 20 kg. Use either figure as a rule of thumb and buy spare. A path 4 m by 0.8 m is 3.2 m². At 50 mm you are near thirteen 20 kg sacks before waste. At 30 mm you still need around eight. A planted 2 m² patch at 50 mm is about eight sacks. Once that looks like a pallet, order a bulk bag. Thin pea on soft soil ruts. A dusting on a bed still lets weeds through. Stop before stone piles against shrub stems.
Amtra Amtra Polychrome 5 kg

Testsieger

Amtra Amtra Polychrome 5 kg
8.6/10about £4.88
View offer

Membrane, edging, and sub-base

On a walked path, membrane keeps decorative stone off MOT Type 1. Overlap the sheets and turn them up at the edging. Under planting, skip fabric if you want self-seeding. It will not stop bindweed, couch or ground elder. Dig those out first. Edging is mandatory for rounded 6–10 mm pea. Timber, brick or metal, with the finished gravel a little below the top, holds the surface. Sub-base is for a path. A planted bed wants cultivated soil, then stone. A centimetre on a houseplant is on ornamental gravel for pots.

Rinse, dust, and topping up

Westland is sold as washed. UK reviews still describe sandy, muddy or split sacks. Rinse outdoors. Damp dusty fines rather than dry-sweeping them. Gravel is not a plant food. Do not pile it against woody stems. Top up where traffic has thinned the path. A 20 kg courier sack suits a small patch, not a 20 m² front garden.

Common questions

How deep should I lay gravel on a path versus a planted bed?
On a planted bed, aim for about 3–7 cm depending on whether you follow Beth Chatto’s thinner local 10 mm or the 5–7 cm Gardens Illustrated range. On a path, merchant tables usually want 35–50 mm of decorative stone over a compacted base. Wickes writes about 25 mm. State a depth, then count bags. Do not copy a pot-top centimetre onto a path.
Do I need a weed membrane?
On a walked path, a permeable membrane is a useful separator under the decorative layer. Under planting, skip it if you want self-seeding. It will not kill bindweed or ground elder. Dig those out first.
How many 20 kg bags for my area?
As a rule of thumb, one 20 kg bag covers about 0.25 m² at 50 mm, or about 0.4 m² at 30 mm. The RHS 25 kg figure of about 0.6 m² at 5 cm is a different bag and density. Measure the area, pick a depth, divide, and round up. Westland is 20 kg.
What goes under the decorative stone?
For a path: excavated trench, edging, optional membrane, compacted MOT Type 1, then pea or chippings. For a planted gravel garden: prepared soil, then the decorative layer, with no membrane if you want seedlings. Do not put a thick gravel sump in a pot and call it the same method.
Why does rounded pea need edging?
Rounded 6–10 mm rolls. Boots, rain and a wheelbarrow move it into the lawn. An edge holds the surface and gives you a level to work to. Angular stone interlocks more. This set is still mostly pea.
Will the membrane stop bindweed?
No. Established perennial weeds come through joints and planting cuts. Membrane can keep stone and sub-base apart. It is not a herbicide.
Should I rinse the Westland sack first?
Yes if the bag looks sandy or muddy, which reviews often report despite the washed claim. Rinse outdoors. Do not dry-sweep fines across a patio.
When is a 20 kg courier bag the wrong way to buy?
When the area needs more than a handful of sacks, when you cannot lift 20 kg, or when you need a named angular grade a merchant sells in bulk. Use courier bags for a short path or a top-up, then change supply method.

Related pages

Ornamental gravel

Best ornamental gravel 2026: path pick or tank bag

Ornamental gravel buying guide: check job and grade

Ornamental gravel driveway planning: England rules

Ornamental gravel for pots: thin top-dressing only

Sources

Public UK sources from the research digest, used for this page in October 2026. Prices, stars and review counts are from the twelve amazon.co.uk listings captured on 19 October 2026. A washed claim and a pond-safe line are listing claims. Coverage figures are rules of thumb and do not match each other. This is not a laboratory test.

  1. RHS, gravel gardens (retrieved 19 October 2026)
  2. RHS, mulches (retrieved 19 October 2026)
  3. GOV.UK, permeable surfacing of front gardens (retrieved 19 October 2026)
  4. GOV.UK, permitted development technical guidance (retrieved 19 October 2026)
  5. Gardeners' World, house plant flies (retrieved 19 October 2026)
  6. Gardens Illustrated, create a gravel garden (retrieved 19 October 2026)
  7. Beesley & Fildes, gravel calculator (retrieved 19 October 2026)
  8. HSE, construction sheet CN5, silica dust (retrieved 19 October 2026)