Gardening Tips for Clay Soil

Clay soil is one of the most common types of soil in the UK. Gardening is not always easy. But understanding the soil in your garden can make things a lot less challenging. The better able you are to understand your soil, the better you will be able to garden and grow your own.

In this article, we’ll look at this soil type in a little more depth. We’ll look at the basics, and how to determine whether or not you have a clay-rich soil where you live. Then we’ll explore some gardening tips for clay soil to help you manage soil more effectively, and improve the soil where you live.

What is Clay Soil?

When we refer to clay soil, we are talking about the basic structure of the soil, or the ‘soil type’. Clay soil is soil that predominantly has particles that are less than 0.002mm in size. This distinguishes it from other soil types, like silt and sandy soil, for example, which have larger particles.

It is the size of the particles within the soil that give it its characteristics. The smaller particles in clay soil have a tendency to clump together. Clay soils have a denser, heavier texture than other soil types. They can therefore be more challenging when it comes to gardening in them.

Do You Have Heavy Clay Soil Where You Live?

Gardening well in clay soil begins with an analysis of the soil. It is important to determine whether your soil contains a lot of clay – or just some. Soils extremely high in clay particles are generally referred to as heavy clay soils. There are also clay soils that are clay-loams – soils which have a lot of clay, but also contain other particles of silt or sand.

How problematic the soil is where you live will largely depend upon how much clay there is. It will also depend on how much organic matter there is in the soil. And on other soil characteristics, such as pH level.

To determine whether you have a heavy clay soil, there are a number of steps you should take. You should:

• Consider getting a professional, scientific soil test done. While not usually necessary for domestic gardeners, a scientific soil test can give you a lot of information about your soil that can help you choose the right plants and make other choices in your garden.

• You can also learn a lot about your soil on your own. Take a handful of moist soil/ mud. If you can roll this mix into a ball and then form it into a bendable sausage shape then your soil has a high proportion of clay in it. You can also learn about your soil by putting some into a jar of water and leaving it to stratify. Larger sand and small rocks will settle to the bottom of the jar, while clay particles will settle closer to the top. If the clay layer in the jar is much thicker than the other layers, you can determine that you have a largely clay soil.

• Observation is also key. Just by looking, and interacting, you can learn a lot about your garden soil. Clay soil will be heavy and difficult to dig. You may note that puddles stay for a long time after heavy rains, or boggy and waterlogged areas remain for long periods. After long dry periods, clay soil will become hard, and will often develop cracks or fissures. The weeds and other plants already growing in your garden can also help you determine whether you have clay soil.

The Characteristics of Clay Soil

Heavy clay soil can be a challenge for a gardener. It is:

• Harder to dig/ work than other soil types. (Though as you will discover below, you should avoid digging whenever possible. A no dig approach is best for an organic garden.)

• More likely to become compacted than other soil types.

• Prone to waterlogging and muddiness.

• More likely to become saturated or hard, so water run-off and erosion can become a problem.

• Readier to freeze in winter, and slower to thaw/ warm in spring.

On the other hand, this type of soil can also be very advantageous. The main plus point of a clay-rich soil is that it is incredibly fertile. It contains and retains far more nutrients than other soil types. It is less likely to become nutrient deficient, and far better at holding moisture than other more free-draining types of soil.

To Manage and Improve Clay Soil

Adopt a ‘No Dig’ Gardening Approach

Adopting the right gardening approach will go a long way towards minimising any issues, no matter what soil type you have. Taking a ‘no dig’ gardening approach means you should:

• Avoid digging/ disturbing the soil as much as possible.

• Leave soil bare – keep it covered to avoid problems with water runoff and erosion.

• Try not to tread on growing areas (to avoid compaction).

• Add plenty of organic matter – compost, well-rotted manures, organic mulches including chopped and dropped plant matter, biochar etc…

Choose the Right Plants

The first and most important thing to remember in any garden is that you should always choose plant appropriate to your soil type. Gardeners with this soil type will find that there are plenty of plants to choose from that will suit their growing conditions. Though of course any plants which require free-draining conditions, or which detest waterlogging, should usually be avoided.

You should be sure to:

• Plant ‘thirsty’ trees and plants to take up excess water from the soil.

• Choose plenty of deciduous trees, shrubs and herbaceous perennials that provide sources of organic matter that will improve soil structure.

• Plant densely to make the most of fertile conditions and avoid leaving areas of bare soil.

• Use deep-rooted plants to open up channels down through the subsoil to help with drainage of a clay rich topsoil layer and improve aeration.

• Utilise cover crops’ green manures to protect soil over winter and provide a source of organic matter.

• Grow plenty of edible crops that like clay soil, including shallow-rooted leafy crops that can take advantage of moisture retention and nutrition in the topsoil. Brassicas, which like the way in which clay soil keeps them firmly anchored, are also excellent choices for clay soil. Hungry crops like squash and courgettes, for example, also like clay soil. And legumes like peas and beans can also do very well in this soil type. Plant potatoes and daikon radishes to reduce soil compaction and break up the clay.

Manage Water Effectively

A good planting scheme can go a long way towards managing water in a clay rich garden. But you may also wish to improve things further (especially if you have a severe waterlogging problem) by:

• Making land drains or vegetated swales to direct and manage excess water in your garden.

• Creating rain gardens to improve drainage issues/ waterlogging in other growing areas.

• Making a garden pond. (one of the benefits of a heavy clay site is that you may be able to make a pond or reservoir without the need for a plastic liner – by using pure compacted clay to contain the water in place).

• You may also wish to add a polytunnel. A covered growing area could help by keeping off heavy rains, snows and frosts – especially during the winter months.

A polytunnel can be a great solution for clay soil gardening. It can help you to manage the challenges it brings. And it can also help you to take advantage of the fertility of your topsoil all year round.

Do you have any suggestions for those with a heavy soil? How do you manage it in your own garden? Share your experiences and tips in the comments below.