Unless you are planning to create a 'hard' garden with mostly gravel or paving, it is crucial to find out the type, texture and acidity level (pH) of the soil. Soils may be light and sandy, heavy clay, chalky or limey, or peaty and acidic. The soil type affects the type of plants that may be grown, drainage, and the ease of cultivation tasks such as digging and planting.

Standard soil-testing kits are widely available from garden centres and nurseries for determining the pH level of a soil, although the presence of certain plants may also give an approximate indication: for example, blue hydrangeas, rhododendrons and heathers usually thrive on acid soil.

Topsoil is 'alive' with nutrients, insects and bacteria that plants need in order to thrive, whilst subsoil is, in effect, dead. Topsoil normally overlays subsoil but if recent building work has left it absent or buried, you will need to remove the top layers of subsoil and replace it with good quality topsoil. If the soil surface has been compacted by heavy machinery, forming a hard 'pan' that prevents drainage, you will need to dig the ground over and re-level.

Take a look at our section on soil for more information on its structure, characteristics and problems.