MULCHES SERVE MANY PURPOSES A mulch is a layer of peat moss, shredded bark or any similar material spread on the surface of the soil under and around plants. The application of mulches has many advantages such as improving plant growth, enhancing the appearance of the landscape and reducing time spent in maintenance. Value of Mulches The most common reason for using a mulch is that it will eliminate or at least retard weeds. Where the mulch layer is sufficiently deep, few weeds will grow. By reducing the amount of soil water evaporation, mulches conserve moisture, which is particularly important during droughty periods of the growing season. Mulches aid in maintaining a uniform soil temperature. They act as insulation in keeping the soil warmer during cool spells and cooler during the warm months of the year. By maintaining uniform soil temperatures, freeze-thaw cycles during winter are retarded, and heaving of perennial plants is reduced. Mulching materials increase water-holding capacity of light, sandy soils and increase aeration of heavy clay soils as they gradually become mixed with the basic soil. Organic mulches serve as food for many micro-organisms found in the soil. During decomposition of the organic material, soil micro-organisms secrete a sticky material that promotes the granulation of the soil. The mulch also maintains more stable temperatures so the actively of the micro-organism can prevail at an even rate. Mulching aids in preventing surface soil erosion, particularly if mulch has been established a few weeks. In addition, mulches help keep leaves, flowers, and fruits free from soil, which is important with strawberries, tomatoes, rock garden plants, etc. Application of Mulches The time to apply a mulch is in mid-spring when the soil has sufficiently warmed up for active root growth. As applied before this, the mulch will keep the ground cool and root growth may be slow. If planting is done in autumn, apply the mulch immediately so that the soil temperature will be kept warmer longer. Most mulches should be applied at least 2 to 3 inches deep over the whole area. Herbaceous plants that require winter protection may need an additional 1 to 2 inches in autumn around the crown or base of the plant. Problem of Mulches Weed seeds maybe introduced into the landscape with hay, straw and strawy manure and may serve as a source of weeds. Various kinds of hulls or corn cobs may have grain or seed mixed in. Molds often develop on cocoa bean and buckwheat hulls when they are kept too moist or in shady locations. Stirring the surface of the mulch to aid in drying will eliminate molds. Several materials used for mulching require an addition of fertilizer to reduce the chance of nitrogen deficiency of the growing plants. Wood chips, sawdust, crushed corncobs, straw and shredded bark need additions of fertilizer. Apply a complete lawn or garden fertilizer at the rate of 2 pounds per 100 square feet before application of the mulch. If the foliage of the plants become yellow during the growing season, additional fertilizer should be applied. Types of mulches Sphagnum peat moss is generally available and ideal for mulching evergreens and other plants that grow best in acid soil. Its color is pleasing, it is free of weed seeds, and it remains effective for one to two years,'depending on the thickness applied. Shredded bark makes an excellent mulch that lasts as long or longer than peat moss. Bark chunks are available in various sizes and are valuable in beautification. Straw is used for winter protection and as a summer mulch in fruits and vegetable plantings. It may carry weed seeds and is flammable, so use it away from areas where cigarettes may be thrown. Crushed stone, gravel chip and pebbles are excellent in the landscape for effect in highlighting plants or garden features. They are available in various colors and can be selected to blend in with the features of the home, patio or landscape. Black polyethylene is used primarily in vegetable gardens, and both black and clear poly have been used in landscaping. Neither should be used in the landscape, however, as drying is reduced and wet soils and woody plants are not compatible. Crushed corncobs are used extremely extensively in some areas but do require supplemental fertilizer applications. Buckwheat hulls are fine textured and may blow in windy areas but have a good neutral color and are long lasting. Sawdust is commonly used where readily available. Nitrogen deficiency is almost certain if fertilizer is not applied regularly. Wood chips or shavings decompose slowly and may need additional fertilizer. Fiberglass mats, inorganic in nature, will not rot, corrode or burn and are long lasting but should be covered with bark or similar organic mulch. Salt hay, spent hops, lawn clippings, leaves, sugar cane, cocoa-bean hulls, leaf mold and paper pulp have all been satisfactorily used for mulching and, if available, should be considered.