If you're wondering how much topsoil do I need for a garden landscaping project, there's a simple calculation that experts recommend in order to get it right.
Topsoil can be purchased in bulk from garden centres and DIY stores, but before you buy, it’s better to calculate how much you’ll need so you don’t buy too little, or too much.
The correct amount of topsoil is necessary in order to provide a stable base for laying a new lawn or creating flower beds where the natural soil is non-existent or of poor quality.
We get the lowdown from gardening experts on how to calculate your topsoil requirements, and offer their advice to ensure you buy the right type for your garden task.
How much topsoil do I need?
Whether you're planning to level a garden or lay turf, the easiest way to work out how much topsoil you need is to multiply the length and width of your plot by the depth of topsoil you require. If you're unsure about the depth you need, keep scrolling as this is covered in more detail below.
To start, measure the dimensions of the area you want to cover in metres. Do this by measuring the length and width, and then multiply these figures together – length × width. This will give you a value in cubic metres.
Amount of topsoil = depth (length x width)
For example, 5m long x 5m wide x 0.1m deep (10 centimetres) = 2.5m³ of topsoil needed.
Next, you may need to convert this into litres. Which is extremely simple as 1m³ = 1000l
Shop topsoil for your project
A 600l bag of topsoil - ideal for a 0.6m³ area, this is a good all-rounder topsoil for most jobs such as turfing, flower beds and vegetable gardens. It contains a controlled slow-release fertiliser.
Specifically formulated for laying turf and grass seed. It's free-draining as it contains sand and soil conditioners.
For smaller garden projects like over-seeding this 25l bag will cover an area of 0.5m at a depth of 50mm.
The recommended depths of topsoil
Topsoil varies in depth increments from very shallow (0-25cm) to very deep (150cm+), and a number of factors will influence the recommended depth of imported topsoil.
These include existing soil type and its quality: for example, if your existing soil is of good quality, you may only need a shallow layer of topsoil to bring the depth up to a level surface. But with poor-quality soil, you may be better off importing the full recommended depth of topsoil.
Another key consideration is what you’re going to use the area for, such as creating lawns, general gardening or vegetable growing.
Topsoil for turf or sowing grass seed only needs to be in the very shallow category, around 10cm.
But for general gardening or vegetable growing, John Dempsey, gardening expert from Housetastic, has this advice: “I’d recommend a layer of around 3-4 inches (approximately 100mm) of topsoil for general gardening and vegetable growing.
“If the soil is particularly dry or lacking nutrients, then I’d recommend around 5-8 inches (127 – 200mm), to help enrich the soil and increase fertility and growth.”
Types of top soil
Topsoil is available in three different grades: economy, general and premium, and working out which one best suits your needs is important.
- Economy is ideal for developing turf and levelling your garden
- General purpose is sterilised and screened, and therefore higher quality, which is ideal for most garden projects, from garden beds to laying a new lawn
- Premium is the best quality-grade topsoil, making it perfect for growing vegetables and encouraging young or damaged lawns to grow.
“If you are looking to grow plants or vegetables, a number of varieties of topsoil can be used, but you should check which vegetables are suitable for growing in each type of topsoil before investing,” adds Jack Sutcliffe, co-founder at Power Sheds.
FAQs
How Is Topsoil Different From Garden Soil?
Topsoil refers to the uppermost layer of soil on the surface of the earth. While its textures vary, it is generally a combination of sand, silt and clay, and can be used for a variety of low maintenance garden ideas.
Garden soil, meanwhile, incorporates a mixture of soils and textures that targets a particular type of garden or plant, such as herb gardens.
“Do your research on what soil you need for your garden, as it isn’t a one-size-fits-all approach,” says Sutcliffe.
“You need to have in mind the purpose of your topsoil and pick a variety (from sandy, clay, silty, chalky and loamy) and depth that suits the plants or vegetables that you intend to grow or the type of turf you intend to lay."
If you're about to undergo some building work, it's crucial that you protect your topsoil. Why not have a look at our expert guide on how to protect your garden during a build.
