Garden Jargon Unravelled | No. 4 | Understanding Soil

Earth, Mud, Dirt, Ground, these are all terms for what a gardener calls Soil. Its properties change when it reacts with water, being a sticky nuisance on our boots when it’s too wet, or blowing as dust in our eyes if not enough water is binding it together.

Most soils are a mixture of the mineral particles clay, sand and silt (usually created from weathered rock) and organic matter (which is decomposed plants, animals and manure). The various proportions of clay, sand, silt and organic matter determine the type of soil and its ability to hold nutrients and moisture.

The perfect soil should also contain moisture, air and nutrients, with the major nutrients being Nitrogen (N), Phosphate (P) and Potash (K) plus Calcium, Magnesium and Sulphur. There are also essential ‘trace elements’ that are very small quantities of elements such as Iron, Copper and Zinc which need to be in harmonious balance. We have a range of fertilisers to maintain the nutrient balance of your soil to keep your plants healthy.

Clay soils are made of very fine particles that bind closely together. They are hard when dry and sticky when wet. Heavy clay soils hold nutrients well but can easily become water-logged and are cold in winter and spring. The moisture content of soil is important as plants need water, but also air, so if the soil is too wet, it will restrict the amount of air available to the roots and sometimes plants will die through being over wet, bizarrely exhibiting the symptoms of drought, as their roots rot and so they cannot take up water. If you can roll your soil into a fine sausage of less than 2mm, you have a heavy clay soil! You can improve the texture of a clay soil by adding more organic matter (such as manure) or using Clay Breaker Pellets. The roots of roses are also good at improving drainage in clay soils.

Sandy soils are made of much coarser particles and drain well but don’t hold nutrients well.  The addition of horse or farmyard manure can help improve the structure of sandy soil.

Silty soils have fine particles but not as fine as clay. They are fertile, light and hold moisture well but are easily compacted.

Loam soils are the perfect blend of sand, silt and clay and have the benefits of holding moisture and nutrients well but also drain quickly after heavy rain.  They are also easy to dig – the gardener’s dream soil.

Peat soils have a very high (sometimes 100%) organic matter content and can be very acidic. They are not usually found in gardens.


Roger Eavis