PEAT - is made up of partially decayed plant material, usually in wet areas. It is composed mainly of wetland vegetation: principally bog plants including mosses, sedges and shrubs and has been used extensively as a growing medium/soil improver for many years.

The commercial extraction of peat at existing rates is considered by some people to be environmentally unsustainable as it removes peat at a much faster rate than it accumulates leading to the irreversible destruction of peatlands. This premise however has been challenged by a number of studies.

Many viable peat alternatives exist which are either completely peat-free or of reduced peat content. However many plants have evolved to grow in a peat environment e.g. Azalea (Rhododendron) and growers find that growing seeds or cuttings in peat is a necessity.