Bark Mulch Reduces Water Loss and Reduces Weeds
Bark dust mulch not only improves the appearance of shrub and tree beds, but reduces water loss and weed sprouting. The most common bark is from Douglas Fir trees. It is reddish brown in color, but ages to a darker brown. Hemlock bark is a darker brown color and ages to almost black. They are of equal effect in reducing water evaporation loss from the soil. They also work equally well in reducing weed seed sprouting by preventing light from reaching weed seeds in the soil. A gradual buildup of mulch over a period of years will allow plant roots to adjust by growing into the mulch. Adding several inches at one time, especially near tree trunks, can damage plants.
Allen Wilson
Allen has been writing about gardening for over 30 years. He is a retired professor of Horticulture.