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What size soil blocker should you buy first in the UK

Updated: October 2026

You want compost cubes instead of another stack of plastic cells. The first decision is what size soil blocker to buy, not which brand leads a table. A four-cell press of about 50 mm (2 inch) is the usual first tool for UK seed starting. A twenty-cell 20 mm mini is for germination and nesting, not for tomatoes or cucumbers on their own. Prices for the seven amazon.co.uk presses sit on the [Soil blocker comparison](/hub/fertiliser-soil-and-bark-mulch/soil-blocker). This page stays with size, steel versus plastic, and what else belongs in the basket. A qualifying Amazon purchase can earn a commission at no extra cost to you.

You want compost cubes instead of another stack of plastic cells. The first decision is what size soil blocker to buy, not which brand leads a table.

Our top picks

nanovi Nanovi 4-cell 2 inch soil blocker

Best overall

nanovi Nanovi 4-cell 2 inch soil blocker
8.8/10about £30.55
View offer
QWORK QWORK 4-cell 2 inch soil blocker

Best value

QWORK QWORK 4-cell 2 inch soil blocker
8.6/10about £19.98
View offer
Lyreh Lyreh 20-cell 3/4 inch soil blocker

Alternative

Lyreh Lyreh 20-cell 3/4 inch soil blocker
6.0/10about £28.99
View offer
On this page
  1. 1.Which size first
  2. 2.Steel, iron or ABS
  3. 3.Pins, inserts and kits
  4. 4.What to put in the basket

Which size first

The Mini 4 class makes four cubes of about 5 cm, sold as 2 inch. The Micro 20 class makes twenty cubes of about 2 cm, sold as 3/4 inch. Official Ladbrooke pages put Mini 4 at four 5 cm blocks, 0.75 kg, from £31.50, and Micro 20 at twenty 2 cm blocks from £25.00. Those prices are market context. An Amazon 2 inch clone is not a Mini 4 just because the cube is the same width. Buy the 50 mm press first for brassicas, lettuce, herbs, or tomatoes that stay in one cube until they go out. The 20 mm mini earns its place when you nest a germinated cube into a 50 mm block. Named picks sit on the best soil blocker page.

Steel, iron or ABS

Zinc-plated or galvanised steel is the default for repeat use, because the grid stays rigid when you press twice. Rinse, wipe, and air-dry. Zinc plate rusts if you store the tool damp. Do not buy stainless because a page asks the question and then prints galvanised in the technical field. QWORK is £19.98 (galvanised, 800 g), Transplant £21.00 (galvanised, 910 g), Moendergo £27.99 (galvanised kit, 2.26 kg), and nanovi £30.55 (zinc-coated, 1.11 kg). YUKERMARB is an iron 4-cell at £76.09, 1.26 kg, with no star line. DONGKER's ABS listing is £16.89 and 100 g, and its one UK review lasted three attempts. QWORK and Transplant sit near the official Mini 4's 0.75 kg. Moendergo is heavy for a windowsill.
nanovi Nanovi 4-cell 2 inch soil blocker

Testsieger

nanovi Nanovi 4-cell 2 inch soil blocker
8.8/10about £30.55
View offer

Pins, inserts and kits

A seed pin is a dimple so a seed sits in a hollow. nanovi prints three pin sizes: 0.82 x 0.43 inch, 0.43 x 0.39 inch, and 0.66 x 0.66 inch. QWORK uses weld-in steel beads and is the press only. Transplant has a fixed hole, and one review says larger inserts were missing. Moendergo adds three plastic inserts and a seeding kit. Lyreh forms a pit in each of twenty cells and adds a five-outlet dispenser. YUKERMARB and DONGKER do not state pins. Inserts matter when you already own both sizes and will nest. Do not assume an Amazon 2 inch clone takes a Ladbrooke insert. The Median Gift Set at £99.75 is market context and is not in this comparison. If the mix is wrong, no pin will save the cube. How you charge and eject sits on how to use a soil blocker.

What to put in the basket

Put a four-cell steel press of about 50 mm in first, then a 6 mm sieve, a trug, and a watertight tray with a 10-15 mm gap between cubes. A rose washes edges off. Skip a 20 mm mini until you will nest, skip ABS for more than a weekend, and skip the £76 iron listing until a cube holds. Entry steel here is QWORK at £19.98 or Transplant at £21.00, with nanovi at £30.55 if you want named pins. Official Mini 4 from £31.50 is the UK-made size reference, not a product we compare here. Weed fabric, a potting mat, or a soil-pipe valve is the wrong search hit.

Common questions

What size should I buy first?
A four-cell press of about 50 mm (2 inch). That is the default for home seed starting in the UK and matches official Mini 4 cubes of 5 cm. A 20 mm twenty-cell mini is a second tool for germination and nesting, not the first buy for tomatoes that stay in one cube until they go out.
Is a 20-cell mini enough for tomatoes?
Not as the only pot. The Lyreh 20-cell listing has a United Kingdom review that says the mini blocks are not large enough for tomato or cucumber seedlings. Use 20 mm cubes to germinate and nest into a 50 mm block, or sow tomatoes straight into the larger cube.
Should I buy steel or plastic?
Zinc-plated or galvanised steel for repeat use. The ABS listing (DONGKER, £16.89, 100 g) has one UK review at 1.0 that lasted three attempts. Plastic is a weekend trial. If the frame snaps in normal use, that is a Consumer Rights Act 2015 return.
Do I need cube inserts on day one?
No. Official inserts fit Mini 4, Multi 12 and Multi 6, and Mini 5 cannot take them. Amazon 2 inch clones do not print Ladbrooke insert fit. Buy inserts only when you already own both sizes and will nest, and do not assume a clone takes the official part.
Why is Mini 5 sometimes cheaper than Mini 4?
Mini 5 is a different official size and is too small for the cube inserts that nest a Micro 20. The lower price is that limit, not a reason to start there if you want the usual 50 mm cube and later nesting.
Do Amazon 2 inch clones take official Ladbrooke inserts?
The listings here do not say so. Treat insert fit as unproven on those clones. nanovi, QWORK, Transplant, Moendergo and YUKERMARB are 4-cell 2 inch tools in this set, not Mini 4 units with a printed insert spec.
What else do I need besides the press?
A sieve, a trug for a wet mix, and a watertight tray so you can bottom-water. The press replaces the cell, not the tray. A dry bag of multi-purpose compost and an overhead rose are the usual reasons the first tray crumbles.

Related pages

Peat-free mix for soil blocks

Soil blocker

Best soil blocker UK: the top pick and best-value pick

How to use a soil blocker so the cubes do not crumble

Soil blocker vs seed trays: cubes or plastic cells

Sources

Public UK and maker sources from the research digest, used for this page in October 2026. Prices, stars and review counts are from the seven amazon.co.uk listings in this set. A German review line is not a UK sample. Ladbrooke prices are market context from the maker's site. A nationwide shop ban on peat compost has not been enacted.

  1. RHS, how to garden without plastic (retrieved October 2026)
  2. RHS, peat-free compost for seeds and cuttings (retrieved October 2026)
  3. Ladbrooke soil blocker hand tools (retrieved October 2026)
  4. Garden UK, soil blocking in the UK (retrieved October 2026)
  5. GOV.UK, General Product Safety Regulations 2005 (retrieved October 2026)
  6. GOV.UK, product safety advice for businesses (retrieved October 2026)
  7. Blackberry Lane, soil blocker notes (retrieved October 2026)
  8. Consumer Rights Act 2015 (retrieved October 2026)