Moisture-retentive, humus-rich, acidic, partially decayed organic matter, with a pH up to 6.5. Used mainly in potting mixes and as a mulch. Derived from sedges (sedge peat) or shagnum moss (shagnum peat) and occurring in boggy, waterlogged conditions. Peat substitutes can be used where appropriate. They include coconut fiber (coir), compost, ground bark, and leaf mold.