Key Takeaways
- Good quality topsoil is key and the cheap stuff should be avoided at all cost – look for quality BS3882-certified topsoil. What you want is a rich ‘loam’, then you can grow just about everything.
- If you want to know what good topsoil looks like, it should be dark, crumbly and with organic matter. If it’s full of rocks, pieces of broken masonry, clumps of grass or sand it isn’t good.
- The more organic material you have in your soil, the better. It’s not an immediate solution but over time it will make just about every soil type better. Any organic matter works – examples like home compost or leaf mold are free, they just need time.
- For help identifying your garden soil type use the ribbon test or the jar test to find out the crucial percentages of silt/sand/clay that make up loam.
- How much topsoil you need depends on what you’re growing. You’ll need a lot less for lawn laying compared to raised beds, for example.
I’ve been gardening and landscaping for over 40 years and I can tell you that good soil is the secret to a brilliant garden. Many people don’t realise how important it is or look after it properly. This article explains what makes soil good & how to make yours better, so your garden will thrive from the start.
What Makes Good Topsoil?
Soil is the foundation of every garden – it holds plants in place and gives them three essential things: water, air and food. Topsoil is the dark, nutrient rich layer at the very top of the ground where most plant roots live. This layer is usually about 30 cm deep. Below is the subsoil, which is harder, more compact and less rich. If you dig deep enough and add compost or other materials to improve it, the depth of your garden’s top soil can be increased.
Virgin top soil contains about 50-60% mineral solids, roughly 5% organic matter & 35-45% air and water. The space for air and water is very important; when soil gets compacted by traffic or vehicles these spaces disappear, making it harder for plants to grow. Digging the soil opens it up so air and water can move through it.
Soil is made from three basic minerals: clay, silt & sand. Clay particles are tiny, silt is slightly bigger and sand is the largest and easiest to see. The best soil mixes all three together – this is called loam. Good soil is alive and full of activity. It contains many creatures – some you can see like earthworms woodlice and centipedes, and others too tiny to see like bacteria & fungi. These help keep soil healthy and should be encouraged.
Soil Types
Understanding the type of soil you have is important in knowing how to cultivate and what types of plants are more likely to thrive and be successful. You can test your soil by rubbing a wet sample between your fingers and trying to form a ribbon. Sandy soil feels rough and gritty and does not stick together. Clay soil feels sticky and forms a shiny sausage. Silty soils are more difficult to determine by this test but generally feel silky and smooth. Loam feels like a mixture of all three. You can also conduct a jam jar test which we cover below.
1. Sandy
Sandy soils drain quickly, are easy to dig and warm up fast in spring which is good for growing vegetables like carrots. They are also poor soils that need extra nutrients added regularly.
- Ideal for well-draining turf and certain plants that dislike wet feet
- Requires feeding and watering more often, especially in Summer
- Adding compost boosts nutrients and structure without harming drainage
2. Clay
Clay soils are heavy and difficult to work with, compacting easily. They stay wet and drain poorly, so they warm up slowly in spring. However, they hold water well through summer & are rich soils. They are good for growing fruit and permanent plants like roses. Improvement focuses on breaking up density and improving aeration and drainage.
- Danger of puddling after rain if not amended
- Incorporate gypsum or coarse organic matter to loosen structure
- Layer with high quality topsoil to create a better root zone
3. Silt
Silty soils are not so common, although occur in certain areas and in particular near rivers. They generally behave more like sandy soils but are richer and less prone to drying out. They are also good for growing vegetables. They can compact under pressure, so light cultivation and organic amendments help maintain drainage.
- Balances drainage and water-holding capacity
- Better for established lawns and mixed borders after moderate amendment
- Watch for crusting in compacted beds. Soil crusting is the formation of a thin, hard layer on the soil surface that develops when raindrops or irrigation break down soil particles, which then seal the surface pores and harden upon drying.
Loamy – the Ideal Blend
Loam is often described as ideal because it combines sand (40%), silt (40%) and clay (20%). It provides good drainage, structure, and nutrient availability for most plants.
- Stable crumbly texture that supports roots
- Excellent general-purpose topsoil
| Feature | Sandy | Clay | Silt | Loamy |
| Drainage | Excellent | Poor without amendment | Moderate | Good |
| Nutrient retention | Low | High | Moderate | Balanced |
| Aeration | High | Low unless loosened | Moderate | Good |
| Ideal use | Turf, drainage-focused beds | Heavy soils, structure improvement | Moderate fertility beds | General purpose gardens |
How to Test Your Soil Type
You can conduct a simple DIY ‘jam jar test’ by filling a jar 1/3 with your soil, then almost the top with water, shaking vigorously and waiting 24 hours. The particles will settle based on their weight and size, with sand at the bottom, silt in the middle and clay at the top. Organic matter will generally float to the top. The ideal percentages are 40% sand, 40% silt and 20% clay.
If you want to learn more about how to conduct a jam jar test check out our article here.
Determining Good Topsoil from Problem Soils
If you suspect that you have problem soil, or just that your topsoil may be in need of improvement, there are different approaches you can take depending on what you are starting with. I talk about the most common problem soils in this article:
Top Soil Improvement
If you are improving your current soil, I recommend following a staged approach. It’s best to plan around the growing season.
- Test soil: identify whether you need more compost or extra grit for drainage
- Choose a soil mix: add compost plus an appropriate amount of grit conditioner
- Incorporate: Add evenly and water in ready for planting
The goal here is combining the right mix of compost, conditioners, and grit that are tailored to your specific soil type and goals. People often ask me how do I make good soil out of bad soil on a budget? I tell them the more organic material you have in your soil, the better; over time it will make just about every soil type better. Just about any organic matter works – examples like home compost or leaf mold are free, they just need time.
Choosing the Best Topsoil for Different Plants
For raised beds or borders, higher organic matter improves soil life and structure over time, so a quality topsoil with added organic matter is advised. That is exactly what our beds and borders topsoil is blended for, and it saves you buying and mixing compost separately. If you are still weighing up whether the bed wants soil or compost at all, I have set out the difference between topsoil and compost, and which job each one is for on its own page.
Choose more alkaline top soils if you are growing brassicas and more acidic options if you’re growing ericaceous plants like rhododendrons and raspberries. If that is the bed you are building, our ericaceous topsoil is the acidic sandy loam I use to fill it. Finding out what pH your plants need is just a search query away.
If you are laying lawn, a finely screened topsoil with good drainage supports quick establishment. That is exactly the job our Premium Topsoil is screened and blended for, at 10mm with a drainage rate of 92mm an hour. Lawn repair is its own job and it does not want a general-purpose topsoil. For filling divots, levelling hollows and over-seeding I would use a 50/50 divot mix, which is half washed sports sand and half soil, screened to 5mm.
In all cases, good commercial topsoil should be properly screened to remove large stones and debris. Products that are certified ‘BS3882:2015’ denotes multipurpose topsoil (suitable for most landscaping, lawns, shrubs, and general planting) and specific purpose grade top soil (for specialist needs like acidic or low-fertility soils) that have met the British Standard requirements for quality, composition and suitability. I always look for this when buying for customers so I can be confident that I’ll get a good result.
Avoid anything that looks grey, sticky, full of rubble or smells unpleasant – these are usually signs of poor quality or contaminated material that will cause you problems later. And one place a standard screened topsoil is the wrong answer altogether is on a roof or a podium deck, where weight is the whole problem and the medium needs to be a blended lightweight roof garden soil instead.”
Topsoil Calculator
If you are looking to purchase topsoil commercially, it’s easy to estimate the volume required with our topsoil calculator just by measuring the depth and area. Our calculators help you to plan for a little extra, which allows for settling and uneven ground.
- Measure the area length and width to calculate the area (cm).
- Choose a target depth in centimetres (cm).
- Pop it in the calculator.
- Allow 10-20% extra for settlement and compaction, especially on larger jobs.
Topsoil Calculator
Results
Total Area: 0 ㎡
Volume Required: 0 ㎥
Volume Required: 0 litres
Bulk Bags Needed: 0
Total Cost: £0.00 (excluding delivery)
The Right Top Soil Depths for Different Planting Schemes
- Lawn laying: 100 mm to 150 mm for a solid root zone.
- Levelling before turf, where the existing soil is already good: 25 mm to 50 mm.
- Raised beds: 200 mm to 300 mm to support deep roots. A raised bed on concrete needs 300mm as a minimum, because the roots cannot go any deeper than the slab. If you are building the bed out of pallets, read which pallets are safe to grow food in before you fill it, because the stamp on the timber only tells you half of what you need to know.
- Border improvement: 150 mm to 200 mm for established plants.
In my experience, topsoil settles with watering, reducing the effective depth after installation. Allow for top-ups after an initial gentle tamping if you’re aiming for a specific height.
| Project | Recommended depth | Grade best suited | Notes |
| Lawn laying | 100-150 mm | Premium or General-purpose | Ensure good drainage and avoid heavy clumps |
| Raised beds | 200-300 mm | General-purpose or Premium | Incorporate organic matter for fertility |
| Border improvements | 150-200 mm | General-purpose or Economy | Focus on texture and weed content |
Next Steps
Now you understand that topsoil is fundamental to successful gardens and what makes a good topsoil. If your soil doesn’t come up to a standard you are satisfied with, you may need to improve it by adding amendments. Alternatively, if you are looking to replace your old topsoil, we have the widest range of ready to use topsoil, compost and soil conditioners. They’re all top quality, at the best prices and BS3882:2015 compliant.
If you would rather talk your topsoil through with a person, ring Outdoor Aggregates on 0330 043 7585. The office is open 7am to 7pm, seven days a week.
Have you ever bought topsoil in? Did what turned up match what you were expecting? Love to hear how it went in the comments.
FAQs
Can you put topsoil over grass?
Topsoil can go over grass as a thin dressing, but not as a way of raising the level. A dressing goes on at 3 to 5mm at a time, and the test is the grass rather than the tape measure: once it is brushed in, the tips must still be clearly visible, because a buried sward dies back. A heavy topsoil on its own also caps the surface, so for patching dips or over-seeding, use a 50/50 sand and soil blend like Divot Mix. To raise a level by more than about 25mm, lift the turf, build up underneath and relay it.
Topsoil versus garden soil versus lawn soil?
There is a significant difference that goes to the suitability of topsoil vs garden soil vs lawn soil. Topsoil is the nutrient-rich surface layer suitable for general use. Garden soil blends often include added organic matter tailored for beds, while lawn soil has a finer texture with added sand for drainage.
Are topsoil and potting soil the same?
Topsoil and potting soil are not the same. Topsoil provides mineral content and structure for outdoor use, while potting mix is a soilless or largely organic mix designed for pots. Potting mix is often made of peat moss or coconut coir, perlite, vermiculite, pine bark, compost, and sometimes fertilizers or wetting agents. Most modern potting mixes contain no soil at all, the exception being the loam-based recipes like John Innes No 3, which are built on sterilised loam and grit and behave much more like soil in the pot.
Is cheap topsoil rubbish?
More often than not, cheap topsoil is rubbish. What a lot of larger stores and cheaper brands sell isn’t genuine topsoil but poor quality excavation subsoil bulked up with things like woodchip, sand, green waste and other organic matter. Always source quality topsoil from reputable suppliers like Outdoor Aggregates. Premium Topsoil is manufactured from single sourced quarried materials blended with certified organic composts so you can be completely confident in buying a fully traceable topsoil that complies with the British Standard BS 3882..
Is the ‘soil’ you buy in bags at the shops intended to be used as topsoil?
Bagged soil from the shops is not intended to be used as topsoil on its own: the instructions on the bag often say ‘to be mixed with existing soil’ or something similar. This is because often ¼ of the bag is made up of wood byproducts (which is basically mulch). This stuff will break down over time, so it does add to and amend existing soil, but it’s not ideal if you want to get started right away. It’s better to buy from a reputable seller like Outdoor Aggregates so you know you’re getting real, high quality soil that’s ready for the job it’s intended for.