How do I buy topsoil without getting rubbish?

Topsoil is the one garden material where the difference between good and bad is enormous, invisible at the point of ordering, and effectively permanent once it is spread. Bad topsoil can bring in perennial weed root, building rubble, contamination and a subsoil texture that will not grow anything, and getting it out again costs far more than the soil did.

Safety

What you'll need

• Somewhere for the lorry to tip
• Twenty minutes to inspect it before it is tipped
• A tarpaulin to tip onto if the drive matters (optional)

Step by step

1. Know the grades.British Standard BS 3882 sets out specifications for topsoil, with 'multipurpose' as the general grade suitable for most planting and specific grades for particular uses. A supplier who can quote the standard and provide a test certificate is a different proposition from one selling 'topsoil' with no further description.
2. Understand screened against as-dug.Screened topsoil has been passed through a mesh to remove stones, roots and debris above a stated size. As-dug is exactly what came out of the ground: cheaper, and it comes with stones, roots and whatever weed seed and rhizome was in it. As-dug is fine for levelling and for filling under turf; screened is what you want for a bed you will plant into.
3. Ask where it came from.The single most important question, and a good supplier answers it readily. Stripped from a construction site is normal and can be excellent. Stripped from a demolition or brownfield site is a reason to see a contamination test. 'I don't know' is a reason to buy elsewhere.
4. Ask specifically about perennial weed and about herbicide.Japanese knotweed, bindweed, couch grass and mare's tail all travel in topsoil, and knotweed in particular is a legal and financial problem you do not want to import. Ask, get it in writing on the order if you can, and inspect what arrives. Where the soil has been blended with green waste or manure, the aminopyralid question applies too.
5. Inspect before it is tipped, not after.Walk to the lorry. Look at the colour — good topsoil is dark brown to nearly black, not orange, grey or yellow, which are subsoil colours. Take a handful and squeeze it: it should be crumbly and slightly moist, not a sticky clay ball, not dust, and not sopping.
6. Look for what should not be in it.Glass, plastic, brick, concrete, tarmac, wire, roots and fragments of fibrous grey cement board. A few small stones are normal. Building waste is not, and cement fibre board fragments are a serious enough sign that you should refuse the load and take advice.
7. Smell it.Good topsoil smells earthy. A sour, sulphurous or chemical smell means it has been stored waterlogged or contaminated, and a load that smells wrong is a load to refuse.
8. Reject on the lorry if it is wrong.This is the whole point of inspecting before tipping. A supplier will take it away; once it is a pile on your drive, removing it is your cost. Be prepared to be firm about this — it is the one moment where you have all the leverage.
9. Compare price honestly, per cubic metre delivered.Loose bulk delivery is cheapest per cubic metre but needs access and somewhere to tip. Bulk bags are more expensive and can be craned into position. Small bags are several times the price and only make sense below about half a cubic metre. Include delivery in the comparison — it is often more than the soil.
10. Improve it before you plant, whatever the grade.Even good topsoil straight from a lorry is a mineral material with modest organic matter. Mix or mulch compost through it before planting, and it behaves like garden soil rather than like fill.

Tips

• Topsoil supplied as part of a landscaping job is where most bad loads arrive, because nobody inspects it. If a contractor is bringing soil in, ask them the same questions and look at it yourself.
• For a raised bed, a blend of topsoil and compost sold as a 'raised bed mix' or 'vegetable soil' is often better value than buying and mixing separately, and better than compost alone by a wide margin.
• Weigh access into the decision early. Twenty tonnes of loose topsoil tipped at the front of a terraced house means barrowing it through, and that is several days of work.
• Local authority green-waste compost sites and quarries often sell soil and soil blends far more cheaply than garden centres, and the material is frequently better.
• Do not buy topsoil in winter if you can wait. It arrives saturated, it is unworkable, and it compacts wherever it is stood on.

Questions people ask