Pine bark is an organic material that can limit water evaporation and the development of weeds. Its weight makes it stable against the wind and its resistance to bad weather gives it the advantage of lasting several years (up to 7 years for the largest calibers) The little extra: its beautiful red-brown color which highlights the foliage of the plants.
Long feared because of the risk of acidification, they have become the preferred mulch for heather plants, but it would be a shame to limit their use to rhododendrons and other azaleas.