Healthy soil with plenty of organic matter promotes healthy plant growth. One of the best sources of organic matter is peat. Peat is a natural, organic soil conditioner. Its unique cell structure helps regulate moisture and air around plant roots, creating ideal growing conditions. Peat retains up to 20 times its weight in moisture, and releases water slowly as plants need it. Peat forms when plant material, usually in wet areas, is inhibited from decaying fully by acidic and anaerobic conditions. It is composed mainly of wetland vegetation: principally bog plants including mosses, sedges and shrubs. As it accumulates, the peat can hold water, thereby slowly creating wetter conditions, and allowing the area of wetland to expand.