Which type of medium is commonly used for planting due to its organic composition and moisture retention capabilities?

Peat moss is commonly used as a planting medium due to its organic composition and exceptional moisture retention capabilities. It is derived from the accumulation of decomposed sphagnum moss in water-saturated conditions, creating a light and fluffy material that can hold several times its weight in water. This property allows it to provide a consistent moisture level for plants, which is crucial for healthy root development and overall plant growth.

In addition to retaining moisture, peat moss also improves soil aeration and structure, promoting better root penetration and reducing compaction. Its acidic pH can be beneficial for certain plant species that thrive in such conditions, making it a versatile choice for various gardening and horticultural applications. As an organic material, peat moss also contributes beneficial microbial activity in the soil, which enhances nutrient availability for plants.

Other mediums listed have different properties: sand offers drainage but lacks moisture retention; sawdust can decompose and provide some nutrients but can also compact and create drainage issues; and rice hulls can help improve aeration but do not retain moisture as effectively as peat moss. Thus, peat moss stands out as the preferred choice for many growers seeking a reliable planting medium.