Breaking Down Mulch

Organic mulches

Cocoa-bean hulls area by-product of the chocolate industry. Use a thin 1-inch layer to suppress weeds. Cocoa hulls work in both formal and informal gardens. (Don't use if you have dogs, as there's been evidence that it can be toxic.)

Enviromulch and other recycled-wood products. Pallets and other wood-waste products are shredded and dyed to make colorful mulch. They tend to last a little longer than other shredded wood or wood chips.

Eucalyptus. This long-lasting wood mulch gained its popularity in the West, where eucalyptus trees are abundant. It holds its color and last for years.

Grass clippings. They're inexpensive, readily available and effective. In spring, cover the ground with 2 inches of clippings. Add additional layers throughout the season, leaving it in place over the winter. In annual gardens, spade it under the following spring or fall—leave it lie in perennial gardens. Don't mulch with grass recently treated with herbicide—it could harm garden plants.

Oyster shells. These are often finely ground and used as a soil amendment in place of lime. They're most readily available in coastal areas.

Pecan and almond shells. One industry's by-product is another's resource. Use a thin 1-inch layer for best results.

Pine needles. In the South, pine needles are harvested, baled and soled as mulch. All evergreen needles make excellent mulch. Rake the excess from beneath your trees and move it into the garden. Use a 1- to 2-inch layer.

Shredded leaves. Fall leaves, including oak and maple, shredded with a mower, make suitable mulch for all plants. They break down quickly, so use a 2- to 3-inch layer.

Twice-shredded wood chips or bark. This mulch tends to break down faster than wood chips, but it's fibrous, so it holds together and stays in place better.

Wood chips. Many types and varieties are available. Some are free from your local municipality or utility company, but you'll have to pay for those of finer quality. Maintain a 3-inch layer for weed control.

Inorganic Mulches

Stone and gravel. These are usually selected for aesthetic value. A wide variety of types, sizes and colors are available. Use a weed barrier underneath.

Rubber mats. The new porous products made from recycled tires provide good weed control, but like all inorganic mulches, don't improve the soil.

Shredded rubber. Made from old tires and dyed to look natural, this mulch is soft, pliable and long-lasting. It's excellent for paths and play areas. For garden use, experiment on a limited basis.

Weed barriers. These spun fabrics let air and water through to the soil below. They're best used beneath inorganic mulches like stone to prevent weeds from growing into decomposed organic mulch and through the barrier.