People looking for natural mulch to benefit their gardens without the use of potentially harmful chemicals have several options. Natural mulch varieties include pine needle mulch, tree and brush grindings, wood chips, bark, compost and stone mulch. The color of natural mulch varies according to the mulch material, age, and moisture content.
Organic mulch generally lasts up to three years before decomposing but will turn gray once it loses its freshness. Both chemically altered mulches and organic mulches will enable soil to retain its moisture by reducing water evaporation from the soil. Both also act as insulation to help maintain a consistent soil temperature, inhibit weed growth, and limit soil erosion. They can be effective in any garden or landscaped area, but organic mulches are especially useful in vegetable and fruit gardens, where they improve the texture of the soil and add nutrients without adding unwanted chemicals.
Pine mulch, or pine straw, makes an attractive mat ground cover and is especially resistant to rain. It does not attract insects, can cover a wide area, and is both inexpensive and easy to apply. It is extremely durable compared to other types of organic material. The desired thickness for pine mulch is from 2.5 inches to 3 inches (6.35 cm to 7.6 cm).
A common natural mulch sometimes available free of charge is the wood chip. Overgrown branches removed from roadsides and other natural debris are often ground into mulch by municipalities and given away. Other hardwood mulch produced from leftover bark at lumber mills includes varieties such as maple, oak, cherry, and birch. The color of these mulches varies from a light brown to a deep, rich brown.
The size of the chips varies, as well. The more the wood is shredded, the finer the chip. Finer mulch does a better job of preventing weeds. Larger chips and bark do not decompose as rapidly as shredded chips, but shredded mulch does not wash away as easily in rain and is, therefore, useful on hills and slopes.
Compost is rich, soil-like matter created as leaves and other organic yard waste fully decompose. It offers an abundance of nutrients for soil. Compost mulch is often available free, because many towns compost fall leaves and offer the composted end product back to residents.
It may not be the first thing to come to mind when considering natural mulch, but stone mulch delivers many of the same benefits as plant-based mulches with the added advantage that it doesn't decompose. That means there is less maintenance required over the years, though stone or rock mulch will not add nutrients to the soil. Tree- and plant-based mulches will nourish the soil over time.