This isn’t the first time I’ve ranted about bad mulch choices and it certainly won’t be the last. But this pictorial cautionary tale is too important to pass up.
We already know that sheet mulches can be death to microbes, plant roots and animals living in the soil underneath. Our newly published research shows that landscape fabric reduces carbon dioxide movement between the soil and atmosphere about 1,000 times more than wood chip mulches do: plastic mulches are even worse. Oxygen movement will be likewise affected. And while gaps and holes in these barriers can lessen the impact, the question remains: why would you use ANY mulch that reduces gas movement? Yet people persist in using fabrics and plastics, usually to “smother” weeds (and that verb should set off alarm bells for anyone thinking about collateral damage to soil life). But weeds are weeds for a reason, and they will eventually colonize the surface of sheet mulches as soil, organic matter, and water collect over time.
So without further ado, here is a case study of what happens when sheet mulch is used for landscape weed control.
These irrigated landscape beds are in Wenatchee, Washington, which has hot, dry summers. As you can see, bark mulch has been used to hide the shame of sheet mulching. And from a distance it looks…okay.