There’s a lot to bark mulches, the following kinds of mulches are used:
Pine needles and leaves hay or straw Crushed stone Wood chips Black plastic sheets or other synthetic products Among natural types of mulches, the bark mulches and crushed stone are also used.
A word of warning, however: In compliance with the UMass Extension service, wood-chips destined to be used as mulch shouldn’t be piled than 10 legs at the compost bin. Exceeding that elevation may cause the pH of your mulch to become overly acidic to the point of damaging plants that come in contact with it.
Note also that it’s not true in assessing the relative merits of bark mulch and wood-chip mulch to say”Wood is wood, so it doesn’t matter which one I use.” The one thing that a fantastic mulch is going to do is keep water. As Linda Chalker-Scott observes bark mulch is not good whatsoever in this capability:
“Bark is the outer covering of the shrub and is significantly suberized to prevent water loss. . .Wood chips, and on the other hand, consist of the inside wood, which is not suberized and has the capacity to soak up and hold moisture” (Chalker-Scott clarifies that suberin is a wax-like material ).