The answer to 'why is my mulch dying plants' is that too much or the wrong type of mulch can suffocate and smother plants, leading to their decline and death. Mulch that is piled too high or made of dense materials like wood chips or bark can block air and water from reaching the soil and plant roots, causing them to weaken and die.
Common symptoms of mulch-related plant death include wilting, discoloration, and stunted growth. To prevent this, make sure to spread mulch no more than 2-3 inches deep, and choose a lighter, more breathable material like shredded leaves or pine needles. If the problem persists, you may need to remove the mulch and aerate the soil around the affected plants.