Using Mulch to Conserve Water One of the best methods of growing healthy plants and conserving water is to use mulch in the landscape. Mulch is a protective ground covering that saves water, reduces evaporation, prevents erosion, controls weeds, and in the case of organic mulches, enriches the soil. Mulches can be classified as organic or inorganic. Mulching reduces soil moisture loss through evaporation. Mulch also reduces the soil’s exposure to wind which also reduces water loss through evaporation. The insulating quality of mulch helps to keep the soil cooler in the summer and warmer in the winter. By maintaining more even soil moisture and temperature, mulch promotes better root growth and plant health. Mulch also helps to reduce rain splash and runoff, which can help to prevent erosion is steep areas. Mulch also suppresses the growth of many weeds. A 3- to 4-inch layer of organic mulch should be sufficient to prevent sunlight from reaching the soil, thereby reducing the chance of weed growth. Any weed seedlings that do manage to germinate and break through the layer of mulch are easily pulled. A mix of coarse and fine mulch will help reduce seed germination. Since some mulch decomposes over time, it will need to be replenished or replaced periodically. There is no need to remove the old and replace with new mulch, since soil organisms will work the decomposing organic matter into the soil, increasing the health of the soil.