Mulching can have many benefits to your garden.  Proper mulching can reduce weeds, add nutrients to the soil, improve soil texture, provide temperature control in the soil, protect plants from frost heaving, protect plants from disease, warms the soil in the spring to promote earlier plant growth, makes lawn maintenance easier, encourages earthworms, helps retain soil moisture, reduces soil erosion and loss, and is appealing in appearance.  All of these things benefit the garden, but improperly added mulch can cause problems that can reduce plant health and possibly even lead to the death of plants.  The three most common mistakes that people make are adding too much mulch, mulching up to the trunk or stem of the plant, and adding dry mulch to dry soil. Too much mulch can create a barrier of decomposing mulch that restricts oxygen and water from entering the soil or can retain trapped moisture, which will rot plants.  Either situation can be detrimental to the health of plants.