Mulch in Garden White and Gray

Asked July 23, 2018, 8:17 PM EDT

Hello! First of all, thank you for providing this resource to the community. I am writing as my family’s landscaper has been using dyed mulch. This year I started to learn more about mulch and asked him to use non dyed mulch & asked why type of wood ect. He claims he does not know. Easily in the summer the mulch started turning white in areas and grey in others. The mulch from previous years does not decompose, new mulch is placed over. The munch under the new mulch is the clumsiest and compleatly white. I am worried there may be many chemicals in this mulch as I don’t trust this landscaper (my parents do). Is there a way to identify is this is mold, discoloration, or chemicals from bad mulch from the photos? Additionally, is there a place I can have this mulch tested to see what exactly we are using in our yard. It is not one portion that is discolored, burneverywhere and we have about .1 acres mulched. Thank you!

District of Columbia

1 Response

What you are seeing is not uncommon, especially in a wet year. Hardwood mulch is an organic product that will break down over time. The discolorations and white areas are some of the ways this is happening, as harmless and natural decay fungi do their thing. The prolonged wet weather and humidity resulted in a larger and faster mushroom/fungi blooms this year.
Mulch normally can take years to break down into compost/soil. It depends on how large the pieces were and other environmental conditions. Colored mulch may take longer.
You don't need more than 2-3 inches over plant and tree roots, and it should always be pulled back from contact with the stems, crowns or trunks of plants. Too much mulch can smother roots.

You can't tell what most wood mulches are made from other than maybe pine bark nuggets, or hardwood mulch-- which could be any number of trees.
If you like, try using a rake to fluff up and turn over the mulch, which can kind of renew the look and hide where there may be some discoloration.

We would not worry about the chemical components. What you are describing sound and looks normal.