United Mulch and Soil Double Ground Redwood is an all natural product coming straight from nature. This product is professionally screened to become a chunk bark nugget and then screened a second time to pick out the wood material for a cleaner product. Double Ground Redwood Bark, with its relatively smaller chunks, creates a very porous medium more subject to quick drying, even in a large, specimen-size container. It is frequently used for large specimen plants, and for those which prefer a very open, rapidly drying mix.