Soil Issues

The strength and health of your plants depends on having good soil. Before you embark on any planting project, you need to know what type of soil you have. Most soils will require some kind of improvement and you can find out what you need to do to it by ascertaining what kind of soil you have. Soil type is also linked to the type of plant you will be able to grow. For example, certain plants cannot tolerate acidic soils, while others thrive in it.

Soil is made from humus (organic matter), which keeps the soil fertile, provides nutrients and keeps the soil aerated. Soil also contains three distinct particles: sand, clay and silt. The particles vary in size and dictate aeration, drainage and nutrient retention.

The first 30-60cm of your soil is the topsoil and contains the most nutrients and organic matter. After that, you will find the subsoil, which lacks nutrients and humus. In some instances, for example on new housing estates, the topsoil and subsoil are virtually the same - that is when one needs to incorporate well-rotted bulky organic manure to improve the situation. Alternatively, topsoil can be purchased.

So what are the different types of soil you may find? The following is a guide to show the six different types of soil, their qualities and what it means for your garden.

Clay Soil

Clay soils are hard to cultivate and work. They are sticky when wet, hard when dry and slow to warm up. Clay soils have poor drainage and little air penetration. However, they usually retain nutrients well so if drainage is improved plants will bequite happy. To find out if you have clay soil, simply squeeze a small amount between finger and thumb. If the particles slide readily and the soil looks shiny and sticky there is a high clay content. If you squeeze a handful together it will form and hold a clump.

Adding organic matter will improve a heavy clay soil because it will aid drainage and aeration.

Asters, Weigela and Chaenomoles are more than happy to live in clay soils.

Sandy Soil

Sandy soils have good drainage and aeration. They warm up quickly and are easy to cultivate. However, they can dry out quickly and do not retain nutrients well due to rapid drainage. To ascertain if you have sandy soil, squeeze the soil between your thumb and finger. If there is a high sand content, the particles will both look and feel rough. If you squeeze a handful it will not form or hold a clump.

You can improve sandy soil by adding organic matter to help hold moisture and therefore enhance the nutrient levels.

Cytisus, Lavatera, Cistus and Hibiscus are happy in sandy soils.

Silty Soil

Silty soils have particles that are intermediate in size between clay and sand. They are well-drained soils and are smooth and soapy to touch. Silty soils are richer in nutrients than sand and easier to cultivate than clay. However, the soil structure can become weak and easily compacted. If correctly managed, silty soils can be good to work with.

Again, the addition of good organic matter can improve the soil texture.

Mahonia, Phormium, Vitis and Nicotiana are happy to live in silty conditions.

Peaty Soils

Peat is made up of partially decomposed organic matter. Peaty soils are dark and fibrous with no sand or clay particles. They are poor in nutrients and are acidic. They retain water well but may require drainage systems. Peaty soil feels spongy to the touch.

Adding lime, nutrients and coarse sand or grit will improve the soil.

Erica, Hamamelis, Camellia and Rhododendron will all thrive in the acidic conditions of peaty soils.

Chalky Soil

Chalky soils are alkaline. They are usually stony and have good drainage. Chalky soils are usually on top of a chalk or limestone bedrock, which means that minerals such as iron and manganese become unavailable to plants, resulting in poor growth.

The addition of fertilisers will improve this type of soil.

Syringa, Dianthus and Philadelphus can be grown in chalky soils.

Loamy Soil

This is the ideal soil to which all gardeners aspire! It contains a mixture of sand, silt and clay, plus organic matter and plant nutrients. It has a good structure, drains well and is easy to cultivate.

This type of soil will support just about any type of plant!

Soil Type Test

Add half a handful of soil to a large glass jar. Fill with water and stir well. Leave this to settle for a couple of hours and then look to see what the soil particles have done. Their reaction will tell you what type of soil you have.

If the water is mainly clear and sandy particles have formed a layer on the bottom you have sandy or gravelly soil.

If the water is cloudy with a thin layer of particles on the bottom you have clay or silty soil.

If there are many bits floating on the surface, the water is slightly cloudy with a small amount of sediment sitting on the bottom you have peaty soil.

If there is a layer of white, gritty fragments on the bottom and the water is a pale greyish colour you have chalky soil.

If the water is reasonably clear with a layered sedimentation on the bottom you have loamy soil (and a very happy gardener you will be!).

Acid or Alkaline?

As mentioned throughout this guide, soils can also be acidic or alkaline which has a bearing on what you can grow. This is all based on soil pH. Acid or "ericaceous" soils have a pH between 1 and 7. Alkaline or "limey" soils have a pH between 7 and 14. Neutral soils, such as clay, are pH 7.

Most plants prefer a pH of 6.5 to 7 - at this point most nutrients are readily available. However, there are plants that need acidic conditions (for example, heathers) and some plants that need alkaline conditions (for example, saxifrages).

A pH test can confirm what kind of soil you have. Call Horticolour now to enquire!