A wide number of things can be used as mulch. Woodchips are the most common, but there are plastic and rubber mulches, gravel, even straw or pine needles. But for this, we’ll talk specifically about the benefits of wood mulch. Mulch should be applied when the soil has already been wet down, and laid in a layer 2-3 inches thick for best results. Using mulch in the landscape offers a number of benefits, including:
Conserves moisture - Any new planting should be mulched to conserve moisture for new plants. Existing beds also benefit from this action, but new plantings are the most vulnerable to water stress. Wood mulch slows evaporation of water from the soil, leaving it available for longer for your plants. Running a soaker hose under your mulch is a great way to get water right where your plants need it and keep most of it from being lost to evaporation.
Smothers weeds - A thick layer of mulch will help smother unwanted weeds. All existing weeds should ideally be removed from a planting bed before mulching. Mulch will prevent existing weed seeds and weak perennial weeds from being able to grow. New weed seeds may blow or drop in to the bed and sprout on top of the mulch, but they are much easier to remove when they are noticed.
Prevents erosion - Mulch keeps top soil from running off in the rain. It also prevents the leaching of nutrients like nitrogen, potassium and phosphorus from the soil, meaning less fertilizer will be needed to keep plants looking their best.
Feeds the soil - Wood mulch, as well as pine needles or straw, eventually decompose. While that may be seen on the surface as a draw back, it actually improves the soil it covers over time, adding additional organic matter. The organic matter in the soil is what holds water and nutrients, making them available to your plants.
Regulates soil temperatures - In the summer, mulch shades the soil and help keeps it cool, while in the winter it insulates and modulates extremes of cold. This is especially good for shallow rooted plants like Azaleas, Rhododendrons and Leyland Cypresses, as well as marginally hardy plants like Loropetalum, Camellias, Rosemary and Figs.
Looks great - Garden beds covered in a neat layer of mulch look nicer than those with bare soil. They look neat and well cared for.
The kind of wood mulch you choose is largely personal. Undyed brown mulch is a cost-effective option that still offers all of the benefits. Naturally dyed red or black mulch give a more polished appearance. Cedar mulch breaks down more slowly and is unattractive to certain insects. Pine bark mulch is perfect for areas with acid loving shrubs like azaleas, pines, rhododendrons and hollies.