Peat moss, when it makes up one-third to two-thirds of the soil, is a good choice for potted plants. Peat moss holds several times its weight in water, and it supplies water to the plant on an as-needed basis. It helps the soil retain nutrients often lost during irrigation.
Peat moss is also free of weed seeds, bugs and parasites that are often present in composted soils. Acid-loving plants, such as radishes, sweet potatoes, blueberries and flowering dogwood, thrive in the slight acidic pH balance afforded by soil mixed with peat moss. Peat moss does not easily break down or get pressed and solid, so it lasts for years.