The soil type in your garden can make or break your plans for a successful garden design. Your plants will only be as successful as the preparation and planning that you, the gardener, put in! Rather than thinking of soil as dirt, you need to start treating it as the life force of your garden. This is where all microbes, bacteria, and microorganisms live, allowing your plants to grow successfully.
The last thing you want to do is spend hundreds of pounds on your garden only to find all your plants wilting or dying. Establishing the type of soil is paramount in making sure that you're selecting the right plants, fertiliser, and conditions for growth.
Let's examine the types of soil you may encounter and how best to work with them during gardening.
The perfect Loam is a mix of inert and organic matter, open, moisture-retentive, and easy to work with!
Understanding why soil is such an important part of your garden is essential. Often soil is confused with dirt or garden compost. However, the soil is neither of these. Soil is its own organic living organism. Dirt is inert material, and compost is organic matter that breaks down. Let's have a closer look at the key soil terms below.
Bits of inert debris, grit, rock and sand with no organic, i.e. living matter.
Soil is a complex mix of particles, minerals, living organisms, dead organic matter and bedrock (ground-down stone). It creates a rich living tapestry perfect for plants and wildlife to thrive in. It's the building block of all successful gardening and garden design.
Loam is the 'near perfect' healthy mix of clay, silt and sandy particles found in soil. Think of it as the ideal mix of balance, but rarely achieved! 40% Sand, 40% Silt and 20% Clay. It’s a subterm for soil.
Compost is organic matter that has been broken down naturally in a recycling cycle. Compost is a nutrient-rich, organic material created by the natural decomposition of plant and animal matter. It is high in nutrients, holds onto moisture, and has a light, airy texture. You can make your own compost at home to help boost your soil health.
It acts as a soil conditioner, fertilizer, and natural pesticide, improving soil structure, moisture retention, and overall plant health. Made from ingredients like kitchen scraps, garden waste, and leaves, composting transforms organic waste into valuable "black gold" for gardens and landscapes.
The soil is composed of both organic (dead and living) and inorganic (mineral) elements. It's created over time and is present in layers known as soil horizons, which, if you dig down, you can see. It is composed of tiny fragments of stone that have been weathered either by the elements or by organisms such as lichen eating away at stone surfaces. These tiny fragments are then built up over time in layers mixed with organic material, creating soil layers.
Organic matter usually comes from trees dropping leaves, plants dying back each year, and animals grazing and dropping their own natural manure. Soil is created by an ever-evolving situation of things growing and then decomposing.
Soil horizons start with the very top organic layer, moving onto topsoil, which most people are familiar with. The next layer is subsoil, and lastly, the parent material consists of solid rocks, sand, and gravel. Don't worry; the science lesson will soon be over, but it is important to understand this to know why knowing your soil type is important.
A gardener is concerned with ensuring that the soil's structure is open, free-draining, contains organic matter (for both nutrients and moisture retention), and is easy to work with. This is a fine balance, and over-cultivation, i.e., digging the soil too frequently, can do more harm than good! This is why a number of gardeners, myself included, are choosing to follow 'no-dig' gardening principles.
This refers to the amount of Sand, Silt and Clay present in a soil sample.
Most people will have heard of sandy, silty, or clay soil types. They may have referred to their own soil as heavy clay or very sandy. These are the mineral fractions of the soil and contain no organic matter.
In reality, the soil is a mixture of these elements along with organic matter and mineral elements all of which dictate how the nutrient or organic elements are contained or lost. The soil type will determine how easily they hold onto water and nutrients. This is why knowing what soil type you are working with is important!
This soil is a mix of 30% sand, 40% silt, and 30% clay, which is nearly perfect!
Loam is the technical term for perfect soil. Whilst there are subclassifications such as sandy loam, clay loam, and silt loam, this general term is used for free-draining soil, which is a 'perfect' blend of the three main components. Very roughly, so the horticulturists don't kill me, loam is
Your soil type will be a mix of Sand, Silt, or Clay. However, the weighting of each element requires a much closer inspection and test. The classifications below are not exact but give you the benefits for each soil type. I always advise that a garden survey is the best way of working out the soil types and pH I offer in all my Garden Design services. Establishing what soil you have will, in turn, lead to your plant selection.
Sandy soil is gritty and free draining like the above image.
Sandy soil feels gritty and coarse, just like sand on a beach. It crumbles easily and doesn’t stick together when dry. It falls apart easily, even when wet. If the soil feels like it has small particles that don’t adhere to each other, it’s likely sandy. Sandy soil drains very quickly, often within a few minutes. This rapid drainage is a key indicator of sandy soil.
Clay soil is fantastically high in nutrients but a pain to work with as it's so thick and sticky.
Clay soil feels sticky and smooth when wet and hard and compact when dry. If you can easily form it into a ball or ribbon, it’s likely clay. Due to its dense structure, clay soil drains very slowly. If water remains for several hours or even days, your soil is likely clay-heavy.
Silty soil feels smooth and silky, almost like flour, due to its fine particles. Silty soil is very fine and contains more nutrients than sand, but it suffers from compaction issues when walked on. It is not sticky like clay or gritty like sand.
The above information should help you assess roughly what soil type you have. Still, ideally, you need to investigate more to understand your soil type. Along with understanding the garden aspect, soil pH, exposure, and other environmental factors will affect your garden design's success. By taking a handful of soil and squeezing it when slightly wet, you can usually get a good idea of what the soil type is.
Squeezing soil will then display one of the three soil types below:
Let's look more closely at soil testing techniques so you can undertake a few simple tests at home and then identify the soil type. A god tip is to take three or more samples from different parts of the garden, especially in larger gardens. This is because the soil type can change in different areas.
There are several ways to test your soil type visually and physically. Here are a few of the methods I use to check soil types in my garden designs.
Examine the Soil Texture. Look at the soil and feel it between your fingers. As discussed above sandy soil feels gritty, silty soil is smooth and silky, and clay soil feels sticky when wet and hard when dry.
Roll a small amount of moist soil between your fingers to form a ball. Squeeze the ball to see if it can form a ribbon or long pencil shape, a bit like rolling it into a worm shape.
Fill a jar two-thirds full with water, add a handful of soil, and shake well. Let it settle for 24 hours. Looking at the three main layers of sediment allows you to work out the amount, percentage or ratio of soil types in your sample.
Dig a hole about 12 inches deep and wide. Fill it with water and let it drain. Refill and observe how long it takes to drain again. This then tells you what soil type you have by how quickly water percolates and moves through it.
This is the easiest way to test soil and requires nothing but getting your hands dirty! Take a handful of moist soil and squeeze it.
Always choose plants that suit the soil you have. That way, you will get the very best out of your garden. Silty soil is in the minority and is usually found near river beds or old water courses. Most soils in the UK are either sandy or clay-based.
It matters because if you, for example, have heavy clay soil, you are going to struggle to grow bulbs, annuals, or lightly rooting plants, as clay is dense and difficult to work with. Given their high water retention, they will simply rot. You must add a considerable amount of organic matter to such soils to help aid aeration and drainage.
You will, however, be able to grow moisture-loving plants such as Iris pseudacorus in clay soil. So you can see how the right plant for the right place comes into play. You won't be able to completely change the soil type; you can only tweak it. It is best to work with what you have got. You will need to assess the
You will need to assess the planting scheme you want for your soil type. It's not impossible to completely change your soil type, but it is highly improbable, given that you would have to remove it all with a digger to replace it fully!
The only way to work with it is through organic dressings and specific planting plans that cater to your soil type. Finding plants that will tolerate or even thrive in your soil type can save you much heartache and ensure you enjoy your garden more than grieving over plants! With my design services, Garden Ninja can help assess soil types and provide suitable planning schemes for this.
So we've talked about the fantastic life force of soil and how soil provides the very elements that your plants need to survive: stability, food and water. However, when the soil has been over-cultivated or walked on repeatedly, it can become compacted like a concrete road of firm grit. It often becomes grey as the top layer develops a soil cap. A soil cap is a hard crust that prevents water and organic matter from entering or leaving the soil. It's a prison for the soil organisms.
Digging in organic matter breaks up soil, aids moisture retention and adds oxygen, as shown in the image above.
If you have compacted soil, the advice is to cultivate it and add organic matter such as compost or lawn clippings. A small amount of this helps keep the air spaces relatively free in the soil. The party starts again with all those microorganisms, and you're ready to plant for success!
Once cultivated, your soil should look healthier, darker in colour, and much lighter to work with. Be careful not to start walking repeatedly over it and compacting it again. If you need to walk that route, consider a path or using boards to protect the soil.
Again, soil pH is incredibly important, showing whether your soil is acidic, neutral, or alkaline. Plants do have a preference for the pH of the soil, so accurately assessing what the pH is can save you time and money with plant choices. There's no point expecting an Azalea to grow in an alkaline soil bed when it is ericaceous or acid-loving; likewise, there is no point trying to force alkaline-loving plants into acidic soil.
Most UK soils are between 5.5 and 7.5. The lower register is more acidic, and the higher the alkaline content of the soil type. However, you may find that different parts of your garden have different PHs. So it is worthwhile to check your garden in different places and record the results.
It must be stressed that most plants are perfectly happy in this 5.5-7.5 position, with a few exceptions.
Some plants prefer acidic or ericaceous soil below pH 5.5. These are usually plants from moors, dry heaths, and peat bogs where acidic conditions are present. They have adapted to take up nutrients available in acidic conditions, e.g., Erica carnea (Winter Heather).
These plants are called "ericaceous" because they belong to the Ericaceae family, which includes popular garden plants like rhododendrons, azaleas, heathers (Calluna), and blueberries (Vaccinium). They require well-drained, acidic soils rich in organic matter and usually have a shallow root system. Ericaceous plants are unable to tolerate high levels of lime or calcium in the soil, which can cause nutrient deficiencies, particularly of iron, leading to chlorosis (yellowing of leaves).
Growing these plants successfully involves using special ericaceous compost and ensuring the soil is acidic enough, either by using soil amendments like sulfur or by watering with rainwater rather than tap water, which may contain lime.
Here are three examples of ericaceous plants:
Calciole or alkaline-loving plants are those which thrive at soil pH above 7. Typically, soils with a pH between 7 and 8.5 are considered mildly to moderately alkaline, while those with a pH above 8.5 are strongly alkaline. This soil type often contains high levels of calcium carbonate or lime, which reduces the availability of certain nutrients, like iron, phosphorus, and manganese, to plants. As a result, alkaline soils are more suited to plants that have adapted to these conditions, often called calcicoles.
Other plants are adapted to more ‘chalky’ soils where alkalinity is high. eg - Convallaria majalis (Lily of the Valley).
Common examples of calcicole plants include:
Alternatively, you can buy over-the-counter soil testing kits. These vary from mixing soil with a solution using litmus paper to assess the PH or electronic probe PH testers. Ideally, you would need multiple checks around each border to ensure you have a proper view of your garden's soil type.
I use an electronic soil pH meter like the one above to measure soil pH, which enables me to quickly work out on client sites the pH of various soil types in any garden.
Take your time, as each test can take around 10 minutes. Map out the pH readings on a plan of your garden site to ensure you know exactly what to plant where.
Yes, you can change your soil type if you really want, but it's not as easy as simply adding things to the soil over time. This only tweaks the soil type but won't fundamentally change it. The only way to change your soil type is to dig it all out and replace it completely. There is a disclaimer: it is incredibly expensive, requires you to remove and replace all soil, and is very bad for the environment to do so.
It is better to work with the soil you have rather than digging up and replacing it. Make tweaks to improve your soil type rather than trying to change it completely.
For Clay Soil: Add coarse sand, gypsum, or perlite to improve drainage and reduce compaction.
For Sandy Soil: Incorporate materials like biochar, compost, or aged manure to increase water retention and nutrient-holding capacity.
For Silty Soil: Add organic matter to improve structure and drainage.
Now you understand everything there is to know about soil types in the garden why not up your garden design skill set too?
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Understanding your soil type and its creation is an important part of becoming a successful gardener. Many gardeners ignore soil at their peril and have lacklustre planting results. By getting to know the soil and treating it as a precious resource, you will become a far better and more mindful gardener.
Understanding your soil type is crucial for effective gardening. It allows you to choose plants that thrive in your garden's soil conditions, ensuring better growth and health. Knowing your soil type also helps you effectively manage watering needs, nutrient levels, pH balance, and soil health.
By understanding the soil's properties, you can implement pest and disease management strategies and plan irrigation systems accordingly. Soil type also influences garden design decisions, such as plant placement and hardscaping choices. Overall, knowledge of soil type empowers gardeners to create and maintain healthier, more vibrant gardens.
If you have questions about your soil type why not Tweet, Facebook or Instagram me with your pictures? You can also follow me on YouTube where I’ve got plenty of garden guide vlogs.
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I am moving to Churchtown soon, can I grow rhododendrons there?
Hi Jean.
You can grow them pretty much any where in the right conditions. Acidic soil and dappled shade are a must if you want them to put on a good show. However, I’ve grown them in full sun but you do need to mulch them each year. Pruning is only light touch and they give a good show all year round. Let me know what cultivars you choose and how you get on. Lee
Very informative guide, clay soil can be quite annoying down south!