What soil goes under turf?
The soil under turf should be loose, good-quality topsoil, and the compacted subsoil below it should be loosened too, because that is what lets the turf root quickly and evenly. The drawing below shows how thick each layer should be, with figures taken from the RHS, Purdue University and Budapest’s District 16 council.
The layers of soil under turf
The drawing shows four layers: the turf with its own thin layer of soil on top, the topsoil that carries it, then the loosened subsoil, and at the bottom the undisturbed original ground. The turf’s roots have to grow down into this topsoil, so it should be loose and of good quality, with no compacted ground left beneath it.
Good-quality turf rolls carry 1.3-1.9 cm of soil beneath the grass, ideally similar in texture to your garden soil. Fill any hollows where water collects before laying, and if you’re planning drainage or irrigation pipes, put them in after rough grading but before the final levelling.
- 1. Turf0-2 cm
Freshly cut turf of even thickness arrives with a thin layer of soil; on good-quality rolls this is 1.3-1.9 cm, and ideally it has a similar texture to your garden soil.
- 2. Topsoil bed2-17 cm
Loose, good-quality topsoil. The District XVI council's turf replacement allows for 10 cm of topsoil and the Purdue University guide for about 15 cm; if your soil is poor, spread a layer of compost or peat about 1-2.5 cm thick over each square metre and mix it into the top 15-20 cm.
- 3. Loosened subsoil17-25 cm
The RHS advises digging or rotavating the soil to a depth of 20-25 cm so that no compacted layer is left; don't rotavate clay soil in wet weather, because a compacted pan forms beneath the tines.
- 4. Undisturbed subsoil25 cm and below
Undisturbed soil. Fill in any hollows where water stands on the surface before you lay the turf, and install drainage and irrigation pipes at this stage.
Laying turf on the prepared soil
- The finished surface should sit about 1.3 cm below paths and edging, so the turf and its soil end up flush with them.
- Lay the rolls on the day they’re delivered, in a staggered pattern and tightly butted together, roll them, then soak them straight away.
- Water the turf every morning for roughly the first 10 days, until it has rooted.
- Do the first mow about three weeks after laying, with the blades set high.
Frequently asked questions
How much topsoil do I need under turf?
Usually 10-15 cm: District 16’s turf replacement project worked with 10 cm of topsoil, and Purdue University’s guide with about 15 cm. If your existing soil is poor, mix in a layer of compost or peat about 1-2.5 cm thick to a depth of 15-20 cm.
How deep should I dig the soil before laying turf?
The RHS recommends digging or rotavating to a depth of 20-25 cm so that no compacted layer is left. In the drawing, this is the loosened subsoil, which runs below the topsoil down to the undisturbed original ground.
How long should the soil settle before laying turf?
At least a few days, and ideally five to six weeks. Then firm it by treading and rake it over in several directions, so the surface is even and firm.
Can I lay turf on clay soil?
Yes, but first dig in plenty of organic matter, such as compost or well-rotted manure, which breaks the clay into crumbs and improves how it handles water and air. Only rotavate it in dry weather, because a compacted layer forms under the blades when it’s wet.
Turf laying with soil preparation included
If you’d rather not prepare the ground yourself, we handle everything from loosening and levelling to laying, rolling and the first watering, and we can also install irrigation under the new lawn. Book a free site visit, we’ll call you back within one working day, and you can write to us in English.
Quicker by phone? Call us on +36 20 944 3464.
