Soil Types

Knowing what type of soil you have will help you to decide which plants will grow best in your garden and how to care for them. 

There are a number of types of soil  - you could have one or more type in your garden, or it could be a mix! See if you can work out which yours is from the descriptions below.

Clay soil 

Clay soil has very small particles and over 25% of these are clay. It’s  heavy, wet and cold in winter, and dry in summer, so clay soil is prone to cracking.  However clay soil is high in nutrients and can be very fertile, despite compacting easily. It can take longer to warm up in spring compared to sandy soils.  You can work out if your soil is predominantly clay by taking a handful when wet and checking if it can be rolled into a long thin sausage shape. It should be sticky and will smear on your hands.

The best way to break up heavy clay soil is to add plenty of organic matter – composted garden waste or purchased mulch etc – which will help break down the clay and allow the plants to take up the nutrients and water more easily.  For very heavy clay soils, you can also add some extra sand to improve drainage.

Silt soil 

Silt soils are similar to clay in that they compact easily but due to slightly larger particles, drain more easily than clay soils.  They feel slippery or soapy when wet but won’t clump easily.  Silt soil also benefits from the addition of organic matter to help avoid the soil compacting.

Sandy soil 

Sandy soils have a lot of sand and very little clay due to the larger particle size. They drain quickly after rain or watering, so easy to cultivate, but dry out very quickly and any nutrients will get washed out easily. They do also have a tendency to be very acidic.  You would be able to feel the grit in a sandy soil, and it can’t be rolled like clay. Very sandy soil will simple flow through your fingers.   To add more nutrients to sandy soils, not only should you add organic matter to help bind the sand particles but also use extra fertiliser to give your plants an extra boost.

Loam

Loam is  a good mix of clay, sand and silt that is easy to work with and fertile. The good drainage helps to avoid compacting, but elements of clay and silt retain nutrients better than sandy soils.  Loam is a really good medium for your plants to thrive in, though adding extra organic matter is also useful, depending on the needs of the plants grown there.

Chalky or lime rich soil

Lime rich soils are largely made up of calcium carbonate, or lime chunks and are very alkaline.  You can usually see some small, white particles of chalk within the soil.  Do not consider growing ericaceous plants in this soil as they will fail to thrive, needing acid soil conditions.   There is little benefit in trying to change the acidity of very chalky soils – if you wish to grow acid loving plants, its best to grow them in pots of planters, in ericaceous soil, and choose lime loving plants to grow directly in your flower beds.  Most chalky soils drain freely but are low in nutrients, so it would always be best to add organic matter and maybe fertilise plants grown in this type of soil. You can of course use a soil test kit to work out just how alkaline or acid your soil is.  A neutral soil would have an pH value of 7.0 with acid being below and alkaline above this value. 

If you are in a location where there has been a range of building or landscaping in the past, it can be difficult to determine the type of soil, and this can change over the landscape, depending on what was there before. In addition, any areas where building rubble has been used beneath the soil as hard core, such as in a new build property,  chemicals can leach out from the rubble and cause the soil to become more acid or more alkaline, and in some cases can damage plants, so this kind of rubble is best removed completely.

To check what type of soil is likely to be in your area, use this link from LAndIS