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Garden sieve mesh size

Updated: 21 October 2026

You are choosing between 3 mm, 6 mm, 10 mm, and 12 mm, and the finer number looks like the better compost. It often is not. A garden sieve mesh size has to match the job, or the holes clog, or the stones you meant to catch fall through. About 10–12 mm is the everyday grade for a heap. About 5–6 mm is the finer grade. A 3 mm mesh is for a small, dry batch. Those bands are a rule of thumb from the listings and UK garden writing, not a British Standard for riddles. The models are in the [compost sieve comparison](/hub/raised-beds-greenhouses-and-compost/compost-sieve). Peter F. kept this page to the hole size on 19 October 2026. We did not measure every disc with a laboratory sieve. If you buy through our links, we may earn a commission at no extra cost to you.

You are choosing between 3 mm, 6 mm, 10 mm, and 12 mm, and the finer number looks like the better compost. It often is not.

Our top picks

Spear & Jackson Spear & Jackson garden riddle

Best overall

Spear & Jackson Spear & Jackson garden riddle
8.7/10about £14.95
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ADEPTNA ADEPTNA five-mesh sieve

Best value

ADEPTNA ADEPTNA five-mesh sieve
7.3/10about £14.95
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n/a 30 cm stainless sieve, 3 mm

Alternative

n/a 30 cm stainless sieve, 3 mm
6.2/10about £12.99
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On this page
  1. 1.Three bands, not one best hole
  2. 2.Compost heap and stones
  3. 3.Finer work and the 5 mm step
  4. 4.Inches on a rectangular frame
  5. 5.Check the disc you were sold

Three bands, not one best hole

Think in three bands. A coarse band, about 10–12 mm, is the compost-heap and stone grade. A middle band, about 5–8 mm, is the finer soil grade. A fine band, about 3–5 mm, is for a small amount of dry material. Shopper round-ups often treat about 6–8 mm as a compromise and 10–12 mm as the stone grade. That is their judgement, not a Royal Horticultural Society rule. There is no tested multiplier for how many times faster 10 mm is than 6 mm. A fixed 10 mm plate does one band. Insert sets, such as 3, 6, and 12 mm, exist so you can change band. They do not make the finest disc the one you should fit first.

Compost heap and stones

For a heap, start at about 10 mm, which is also the 1 cm mesh Gardeners’ World uses on a homemade barrow sieve. The Spear & Jackson listing states 10 mm square holes. Reviews describe holes of about 1 cm and say small stones can pass. That is the grade doing what a 10 mm hole does. If you need every pea gravel held back, 10 mm is the wrong band, and a finer mesh will also catch more twigs. Stones want the coarse end, 10–12 mm, in rigid metal. A 3 mm pan is the wrong first tool. Reviews of the fixed 3 mm sieve at about £12.99 say some buyers found it finer than they wanted. Haxnicks states 10 mm × 10 mm on its own page. The Royal Horticultural Society still warns against homemade mixes for sowing. How you load the sieve is on the how to use a garden riddle page.
Spear & Jackson Spear & Jackson garden riddle

Testsieger

Spear & Jackson Spear & Jackson garden riddle
8.7/10about £14.95
View offer

Finer work and the 5 mm step

Use the middle and fine bands when the batch is small and dry: potting a few containers, grading a trug of sieved soil, or separating a handful you already riddled at 10 mm. The two scoops in this set, at 3.8 mm and 5 mm, are that sort of tool. They are not a heap riddle. A 6 mm screen, as on the Suwimut set and the moonateen bucket sifters, sits in the finer everyday grade. It will still clog if the compost smears. The sourced figure, as distinct from the rule of thumb, is the Royal Horticultural Society’s John Innes note: sieve loam through 5 mm before the heat step they describe, moist soil no deeper than 8 cm, at 71–79 °C for 10 minutes. That is their method for that loam, not an invitation to bake a bucket of compost in a kitchen oven. Do not merge it with times from other booklets. Sieving to 5 mm does not pasteurise anything. The same organisation’s peat-free guidance says homemade potting compost is best avoided for seed sowing because of fungi.

Inches on a rectangular frame

One frame in this set, the rectangular ADEPTNA, labels the discs as 1/4 inch, 3/8 inch, and 1/2 inch rather than millimetres. Those are about 6 mm, 10 mm, and 13 mm. The 1/4 inch disc is the finer grade, close to the 5–6 mm band. The 3/8 inch disc is the heap grade, close to 10 mm. The 1/2 inch disc is a little coarser than 12 mm, so more small stone will pass than through a 10 mm plate. The frame is listed at 40 × 30 × 20 cm and about £14.95. A 13 mm hole is a coarser sort, not a failed 10 mm hole. UK reviews of this frame say the disc can slip, which is a fit problem. That limit is on the garden sieve buying guide. A 6 mm disc still does not make seed compost.

Check the disc you were sold

Labels and discs do not always agree. On the ADEPTNA five-mesh pan, one UK review says the smallest mesh was about 5 mm rather than the 3 mm in the title, and that wires buckled. A ruler across a few holes is enough to see a gap of that size. You do not need a laboratory test sieve, and a garden riddle is not BS ISO 3310. If the disc is plainly coarser than the box, that is a description problem under the Consumer Rights Act 2015, section 11, in the same way a 20 cm pan titled large is. The Haxnicks amazon listing does not state a millimetre size at all, so the maker’s 10 mm × 10 mm page is the figure you are trusting until you look at the mesh. If you cannot see daylight through a hole and judge it against a ruler, you do not yet know which band you bought.

Common questions

What hole size should I use for a compost heap?
Use about 10–12 mm for a finished heap. That matches the 1 cm mesh in Gardeners’ World’s soil-sieve build and the 10 mm plate on the Spear & Jackson riddle. Finer holes hold back more of the compost and clog if the heap is damp. Put the sticks back on the bin. A 10 mm grade is the normal heap mesh, not a failed attempt at 3 mm.
What size is right for stones?
For stones in topsoil, stay at the coarse end, about 10–12 mm, in rigid metal. A 12 mm insert lets more soil through and keeps larger stones. A 3 mm mesh is the wrong first screen. It clogs, and reviews of a fixed 3 mm pan say some buyers found it finer than they wanted. Poly mesh is a poor match for sharp flint, whatever the hole size printed on a maker’s page.
What is 1/4 inch, 3/8 inch, and 1/2 inch in millimetres?
They are about 6 mm, 10 mm, and 13 mm. On the ADEPTNA frame that uses those labels, that is a finer disc, a heap disc, and a slightly coarser stone disc. The 3/8 inch mesh is the closest to the 10 mm plates sold in millimetres. The 1/2 inch mesh lets a little more small stone through than a 12 mm insert. Convert the label, then match the band to the job.
Why does fine mesh clog?
Damp crumbs and small twigs sit across a 3 mm or 5 mm hole and seal it. The same compost will often pass a 10 mm plate. Wet, sticky material balls up, which is why sieving notes tell you to dry the heap first. Knock the mesh clear and use a thinner layer. A finer disc is not broken because a damp spadeful will not go through it. It is in the wrong band for that load.
How do I check a disc that might not match the label?
Lay a ruler across the holes. A disc sold as 3 mm and closer to 5 mm is visible without a laboratory sieve. One UK review of the ADEPTNA five-mesh pan reported that difference, and buckled wires. If the mesh does not match the description, section 11 of the Consumer Rights Act 2015 is the relevant rule. Check the disc you fit today, because a set contains more than one grade.

Related pages

Raised bed compost comparison

Compost sieve

Best garden riddle UK: heap, stones, or folding

Garden sieve buying guide: size, mesh, and metal

Rotary soil sieve vs riddle for more than one bin

How to use a garden riddle so the mesh stays clear

Sources

Public UK and manufacturer sources, last checked on 19 October 2026. ASIN prices and stars are from the amazon.co.uk listings in this comparison.

  1. RHS, How to make your own potting mix (retrieved 19 October 2026)
  2. RHS, Four steps to perfect compost (retrieved 19 October 2026)
  3. RHS, John Innes potting compost (retrieved 19 October 2026)
  4. RHS, Peat-free compost choices (retrieved 19 October 2026)
  5. Gardeners' World, How to make a soil sieve (retrieved 19 October 2026)
  6. Haxnicks, Easy Riddle (retrieved 19 October 2026)
  7. Spear & Jackson, Garden riddle (retrieved 19 October 2026)
  8. Consumer Rights Act 2015, sections 9 and 11 (retrieved 19 October 2026)