I recently spread a thick layer of pine mulch and now several of my plants look yellow and sickly. Do you think it could be the mulch? I don't know if it was composted or not. Thanks for the help.
Sudden Yellowing of Leaves
Certified GKH Gardening Expert
I have not heard of pine mulch causing such a reaction. However, if the layer is too thick, it could be choking off the oxygen allowed to get to the soil and, thus, affecting the plants. Also, if the mulch layer is too thick and the soil doesn't drain well, such as heavy clay, it could be holding too much moisture in the root zone, causing the yellowing of the leaves. I have also seen cases where the pine mulch attacted neighborhood dogs to the area, relieving themselves and spraying the plants with their urine. Thus, burning the foliage just enough to turn the leaves yellow before they die off.