It is amazing how many materials have been tried and used as mulch. We have been asked about shredded wire insulation, ground rubber tires, waste paper pulp, numerous bean and seed hulls, plastic coated papers, spray-on asphalt formulations, and fiberglass mats and fabrics. These are often compared against better known products like sawdust, peat moss, shredded tree bark or the several types of bark nuggets available. The organic types are derived from plant materials or plant by-products such as peat moss or the bark taken from logs at the sawmill. Inorganic mulches can be either manufactured materials like plastic film or natural stone.
Black plastic is probably the best known inorganic mulch product.
Any material that satisfies the requirements of a mulch by controlling moisture loss and weed growth can be used in the garden or landscape planting. The selection of a specific material will be governed to a large extent on where it will be used, appearance and possible cost. Most organic materials have to be applied in a layer 3 to 4 inches deep to be completely effective and this will determine cost in large sites. The inorganic plastic sheets are not too attractive when used alone and should be covered with a textured material in a landscape. In the vegetable garden for the most part, appearance is not all that important, so plastic is a common choice and it works very well.