The answer to 'mulch dying plants' is that there are several common causes for mulch causing plants to die, including poor drainage, excessive moisture, and smothering the plant's roots. Symptoms can include wilting, yellowing leaves, and stunted growth.
To solve this issue, first check the depth of the mulch around the plants. Mulch should only be 2-4 inches deep to allow proper air and water flow. If the mulch is too thick, simply remove the excess. Make sure the soil has good drainage and isn't staying overly wet. If needed, add organic matter like compost to improve drainage. Lastly, pull the mulch back a few inches from the base of the plants to prevent suffocating the roots.