Can refer to either home-made garden compost or seed/potting compost:• Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. • Seed or potting composts are used for growing seedlings or plants in containers – a wide range of commercially produced composts are available, made from a mix of various ingredients, such as loam, coir, peat, sand and fertiliser, although you can mix your own.