Learning the basics about soil types can be one of the best ways to ensure gardening success. If you've found that your planting picks haven't thrived as you expected, despite you providing the best care, you may be choosing the wrong varieties for your soil.
Knowing what grows best in specific types of soil can also help you choose a mix of plants that suits the growing conditions of your garden, particularly if you're about to embark on a new landscaping design.
Soil can range from being either very acidic or alkaline. But, other soil characteristics will also play a part in how well your plants will grow. In this extensive guide we'll dig deep into everything you need to know about your garden soil.
How do you identify different soil types?
The first step to identifying the soil types in your garden is to identify whether it is acid or alkaline. Soil pH varies from around 3.5 (very acidic) to 8.5 (alkaline) – a reading of 7 is considered neutral and the optimum for most plants is 6.5.
"Most plants prefer a slightly acidic to neutral soil, around pH 6 to 7, while lime-loving plants such as lavender, clematis and many brassicas do better in more alkaline conditions," notes Julian Palphramand, head of plants at British Garden Centres.
"A home pH testing kit is also useful for establishing whether your soil is acidic, neutral or alkaline, which can help when choosing plants," says Peter Chaloner, managing director of Cobra.
This Garden Tutor Soil pH Test Kit from Amazon will help you establish which type of soil you have, while another easy way to tell is to ask your neighbours which plants they are growing in their gardens and work out the approximate pH based on what's performing well in nearby soils.
"Also pay attention to what happens after heavy rain, too," says Peter. "Water sitting on the surface can indicate heavy or compacted ground, while very rapid drainage may suggest sandy or free-draining soil. This is particularly important for lawns, as poor drainage isn't always down to soil type; compaction can be a major factor and can often be improved through aeration.”
Get your hands dirty to find out your soil type
“Another simple way to get an initial idea of your soil type is to take a handful of moist soil and squeeze it," adds Peter Chaloner. "Clay tends to feel sticky and holds its shape; sandy soil feels gritty and falls apart easily, while loam is usually crumbly but holds together loosely. Silty soil feels smooth and silky, while peaty soil is typically dark and spongy."
As well as looking at your soil, assessing how moist or dry it is, and how easily you can get your spade into it, you can also try the following simple test if you're still not sure. First, take a sample of soil from about 4–6in (10–15cm) below the surface – if you have a large plot, take a few samples from different areas. If it is not already damp, add a little water so that it's moist but not wet. Then, feel the texture with your fingers before trying to roll it into a ball.
A soil rich in clay will feel smooth and sticky and have a surface sheen like plasticine if you rub it. When rolled into a ball, clay will keep its shape well, and it can be moulded to form a long ribbon. It will also retain a fingerprint mark when you press your thumb onto it.
Sandy soil feels gritty, and when you try to roll it into a ball, it will fall apart. Silty soils have a smooth, soapy texture and will make a loose ball shape but will easily fall apart and cannot be moulded into a ribbon like clay.
A peaty soil feels spongy and won't roll into a ball – drops of water may also come out when you squeeze it. Depending on its exact make-up, you may be able to roll loam into a ball and even a ribbon shape if it's a clay loam, but it will not leave a fingerprint mark when pressed.
If you suspect your soil is chalky, check for the tell-tale signs of white chalk and stony flint in it. You can also add some soil to a jar of vinegar, and if it froths, then you know it contains chalk or limestone and will be very alkaline.
Julian Palphramand is Head of Plants at British Garden Centres. His expertise lies in horticulture with a passion for fostering a love of plants.
Peter is the managing director of Cobra, one of the UK's leading brands of garden machinery, and Henton & Chattell, one of the largest garden machinery distributors in the country. With over 30 years of experience in the industry, Peter is also a passionate enthusiast when it comes to lawn care and seasonal gardening tasks.
6 main types of soil
While all soils fulfil a similar function, there are many different types, and knowing which one you have in your garden will help you to choose plants adapted to thrive in your specific conditions.
Clay and sandy soils are the most common types; silty soils are less prevalent and are generally found on flood basins near rivers or where rivers have previously existed; and peaty and chalky soils are rare in gardens and exist in just a few areas of the country (at least, in the UK).
Although there is no 'good' or 'bad' soil, since there are plants adapted to each type, some can be more challenging to cultivate and may not support as many garden plants species.
1. Clay soil
These soils are made up of a large proportion of microscopic clay particles, which can become compacted, binding together tightly to form large, solid, airless clumps.
They are known as 'heavy' soils, not because they weigh more than others, but because they are difficult to dig – if you have clay, you may not be able to get even your garden spade into it in the summer.
Getting the most from clay soil
Improve the drainage by digging in as much horticultural grit, sharp sand, or even fine gravel dredged from freshwater sources as you can muster.
"Clay soil holds water and nutrients well but can become compacted and waterlogged," adds Peter Chaloner, "so regular aeration can help improve drainage and encourage stronger root growth."
Make sure you also choose the best plants for clay soil when you visit the garden centre to ensure success.
"Clay suits roses, hydrangeas, euphorbias and forsythia, plus crops such as brassicas and beans if it has been improved with compost," advises Julian Palphramand.
Use horticultural sharp sand for improving soil drainage
2. Sandy soil
Sand particles are much larger than clay, and they also have bigger spaces between them that allow water to drain through easily.
"As a result, sandy soil drains quickly and warms up early, but loses moisture and nutrients more readily, meaning lawns may need more attention to watering and feeding, particularly during dry weather," says Peter Chaolner.
Often referred to as 'light' because they are easy to dig, sandy soils also warm up quickly in spring, allowing seeds to germinate and plant growth to begin sooner than in other soils.
Getting the most from it
To give plants the best start, pour compost into each planting hole to the depth of the head of a spade.
Weeds must be kept tightly under control. For minimal maintenance, cover the earth with a weed-proof, semi-permeable membrane, securing it with stakes, then cut slits to plant through. Once planted, cover the membrane in around an inch (3cm) depth of gravel.
Expert tips
As these soils are dry and warm in early spring, they can be ideal for sowing early vegetable crops. The drier conditions, especially in winter, also suit plants such as lavender, rock roses, and olive trees – perfect picks if you're looking for Mediterranean garden ideas.
Perfect plants
"Sandy soil is good for lavender, rosemary, buddleia and root vegetables such as carrots and parsnips," notes Julian Palphramand.
Kniphofia is an exotic choice ideal for coastal gardens. Echinacea purpurea 'Doubledecker' is also a good choice, especially if you're looking for bee-friendly plants for an eco-friendly garden.
Other top picks include achillea, agapanthus, amelanchier, spring bulbs, delphinium, dianthus, fuchsia, geranium, bay, poppy, ornamental grasses, sedum, and thyme.
Keep weeds at bay with an appropriate weed membrane
3. Silty soil
Silt particles are smaller than sand but larger than clay. The gaps between them allow good airflow and drainage while still retaining some water and nutrients.
Getting the most from it
Silty soils suit a wide range of plants, including any that like moist, free-draining conditions. "Silty soil is generally fertile and moisture-retentive but can be prone to compaction, making aeration beneficial," advises Peter Chaloner. Avoid walking on it while wet where possible.
Expert tips
Silt soils are prone to washing or blowing away in the rain or wind. As the RHS suggests, you can add organic matter to this type of soil to make the silt particles more stable. How about giving worm composting a go if you haven't already?
Perfect plants
Julian Palphramand tells us that, "silty soil suits a wide range of plants including hellebores, ferns and alliums, and it is excellent for most vegetables – if it does not become waterlogged."
You can also try aster (including symphyotrichum), birch, dogwood, delphinium, lupin, phlox, rose, rudbeckia, leucanthemum, sweet box, viburnum, willow, and hellebores.
4. Chalky soil
If you have chalk, you will see lumps of the soft white stone, as well as hard pieces of flint. "Chalky soil is free-draining and alkaline, so lawns can be more susceptible to nutrient deficiencies and drying out," says Peter Chaloner.
Many chalky soils are shallow, lying over a layer of chalk or limestone. They are also alkaline, free-draining and relatively infertile. If they also contain a good proportion of clay, they can be water-retentive and contain more nutrients.
Getting the most from it
"As chalky soil is often thin, it suits lavender, clematis, peonies and brassicas, as well as beetroot and spinach with regular feeding," explains Julian Palphramand.
Where you have a thin layer of soil over chalk bedrock, try learning how to plant a wildflower meadow that will thrive in these conditions. Or, try planting small species with shallow root balls.
When planting on chalk, also break up the ground to a depth of 2.5ft (75cm) to allow plants' roots to spread. Honeysuckle, euonymus, and verbascum will all love alkaline conditions.
Consider planting a wildflower meadow using a seed pack like this if you have chalky soil
5. Peaty soil
Rarely found in gardens in the UK, peaty soils are made up of organic matter, such as decomposed plants. Peat is dark in colour, low in nutrients, and water-retentive – it holds on to moisture like a sponge. "It is also often acidic and can encourage moss where conditions remain wet," notes Peter Chaloner.
Perfect plants
"Peaty soil is is best for acid-loving plants such as rhododendrons, camellias, blueberries and heathers, while vegetables such as potatoes and leafy crops can do well if drainage is managed," says Julian Palphramand.
Pieris, blue-flowered hydrangea, heathers, and witch hazel will also all thrive in peaty soils. You can learn more about growing hydrangeas in our guide, but, don't try to grow plants that prefer alkaline conditions such as clematis and lavender.
6. Loams
"Loam is the most balanced soil type, combining sand, silt and clay, and it is ideal for almost everything," notes Julian Palphramand, including tomatoes, carrots, foxgloves and wisteria, as well as most vegetables."
Water-retentive, free-draining, and fertile, it contains roughly equal proportions of sand and silt, together with enough clay to hold moisture and nutrients. As a result, it offers gardeners – and plants – the best of all worlds.
"It is also particularly well suited to healthy grass growth," notes Peter Chaloner which is good of you are planning on large areas of lawn in your garden.
When improving a soil, it is a loam-like consistency that you are aiming to achieve. Sandy loams have freer drainage, while clay loams hold more water, but all types are suitable for many different plant species.
Expert tips
You can make a heavy clay or light sandy soil more loam-like by mulching – see below for more info on how to improve soil.
Perfect plants
Only those that are adapted to very free-draining conditions (such as drought-loving Mediterranean herbs) or bog plants that love lots of moisture (such as candelabra primulas and Siberian flag irises) will turn up their noses to loam. The list of suitable plants is therefore almost endless, and most vegetable crops will also thrive in loam.
Understanding how to deal with sun and shade
“The orientation of your garden can have almost as much impact as the soil itself because sunlight, shade and wind all affect how quickly the ground loses moisture," says Peter Chaloner.
It means that regardless of soil type, you may also need to take extra measures to get the most out of your garden.
How do you deal with hot and sunny soil?
These will be areas like a south-facing bed or border that get the full heat of the sun all year round. Not all plants will survive such conditions, but plants for full sun, such as exotic choices will thrive.
"For hot, sunny soil, the key is to help it hold on to moisture and stop it drying out too quickly," advises Julian Palphramand. "Water early in the day, add a good layer of mulch, and work in plenty of compost or well-rotted organic matter to improve moisture retention."
"During prolonged hot, dry periods, lawns can also benefit from a higher mowing height," adds Peter Chaloner, "as longer grass helps shade the soil and reduces stress on the plant."
Getting the most from it
Having a drip irrigation system, such as this 315 Piece Drip Irrigation Kit from B&Q, or laying a hose with small holes punched along its length through the bed, to drench the soil in the evening when needed can help during particularly hot spells. Mulch the soil with well-rotted manure in autumn and spring with coarse compost or leaf mould to help with moisture retention.
Exotic plants which love the hot sun will need more protection from the winter frosts. The crowns of tree ferns and banana plants must be wrapped in horticultural fleece or hessian.
Top tips
Sunny plots are ideal for many herbaceous favourites – roses, bergamot, and tobacco plants, for example. They are also perfect for hot-coloured tender exotics such as cannas and ginger lilies, but grow them in large plastic pots that, come spring, are submerged in beds, but can be lifted in autumn and overwintered in a greenhouse to avoid frosts.
Perfect plants
Cannas give an exotic feel. Aeonium arboreum 'Zwartkop' is a beautiful succulent. Dahlias will also work well in a hot border. "Crops such as tomatoes, courgettes and beans can also do well if they are watered regularly," adds Julian.
How do you deal with shady and dry soil beneath trees?
"For shady, dry soil, the main problem is often competition for water from tree roots or nearby walls," explains Julian Palphramand. "Improving the soil with organic matter and mulching well will help conserve moisture, but plant choice matters just as much."
Getting the most from it
Before planting, dig a deep hole part-filled with compost, and thoroughly soak the plant's rootball. Water new plants weekly until they establish. Dig in organic matter to increase the moisture retention of the soil, mulching heavily with a thick layer of bark chippings in spring.
In spring and during hot spells, thoroughly soak the ground once every 10 days – this encourages deep root penetration, whereas watering little and often develops weak, shallow-rooted plants.
Expert tips
Under deciduous trees, plant spring-flowering bulbs such as cyclamen, anemones, snowdrops, and narcissi. Create a ground cover of foliage to retain moisture. If planting in terracotta pots, line them with plastic to retain moisture in hot spells, adding moisture-retentive gel granules to the compost.
Perfect plants
"Go for species that are happy in dry shade, such as hellebores, epimediums, vinca, heucheras, geranium macrorrhizum and ferns, rather than trying to force moisture-loving plants to cope," advises Julian.
And, if your lawn is shaded, "this can present different challenges, with weaker grass growth and damp conditions potentially encouraging moss," says Peter Chaloner, "so avoid mowing too closely and consider aerating compacted areas.”
FAQs
How can you improve your garden soil?
The best advice for any gardener is to choose plants adapted to your site and soil conditions. But we all want what we can't have, so if you have your heart set on a plant that likes good drainage but you have heavy clay, or a rose that prefers rich soil and you have dry, infertile sand, you can improve your soil to widen your choices.
"Whatever type of soil you have, the best first step is to add plenty of well-rotted organic matter, such as compost or manure, because this improves structure, boosts nutrients and helps soil hold the right amount of moisture," says Julian Palphramand.
"In clay soil, organic matter helps break up compaction and improve drainage; in sandy soil, it helps the soil retain more water and nutrients; and in silty soil, it can reduce the risk of waterlogging."
Peaty soil also benefits from careful watering and mulching to keep moisture levels steady. Loam is already the most balanced soil type, but even that will benefit from a regular mulch to keep it fertile and healthy.
Covering clay soils also prevents them from forming solid crusts in summer. Humus also coats sandy particles, but in this instance, it acts like a water magnet, allowing them to hold on to moisture for long enough for plants to take it up through their roots.
Apply an organic mulch to clay soils in winter, and to dry sandy soils as part of your spring garden jobs, to prevent winter rains washing it away. Leave a gap around the woody stems of shrubs and trees so that the moist mulch will not rot your plants.
A mulch laid on the soil surface will be taken down and incorporated into the lower depths by worms and other creatures. Here, the organic matter not only improves the structure of the soil, but it also continues to decompose, releasing plant nutrients slowly throughout the growing season.
Another top tip is to protect your soil, particularly those rich in clay or silt, from compaction by never walking across it when it's wet. After rain, put down wooden boards for walking on, which will help to spread your weight if you need to tend your beds while the soil is still damp.
How do I know which vegetables will grow in my soil?
Want to grow your own crops for a delicious harvest next season? As our experts have advised, different veggies suit different types of soil, so here's a quick reminder on what to plant if you're starting a vegetable garden:
- Clay soils suit lettuce, chard, green beans, broccoli, Brussels sprouts, and cabbage
- Sandy soils are good for onions, most herbs, tomatoes, and root vegetables, including carrots, parsnips, potatoes, and radishes
- For silty soils, try broccoli, cabbage, courgette, green beans, kale, lettuce, onion, potatoes, pumpkin, tomatoes, and sweetcorn
- Chalky soils are well suited to radishes, Swiss chard, and sweetcorn
- Finally, if you have peaty soil (but it's not too wet), try potatoes, celery, onions, carrots, and lettuce
Once you've established your soil type, you can then start to think about the design of your garden. Find inspiration in our round-up of cottage garden ideas, or for something that's a little easier to look after, take a look at these low-maintenance garden ideas instead.
The original version of this article previously appeared on Gardeningetc, a sister website to Homebuilding & Renovating.
