Is Dyed Mulch Safe to Use?

You Can Handle It if It's Certified

Image of mulch and shrubs along a house foundation.
Many gardeners prefer the mulches that have been dyed black to those that have been dyed red. David Beaulieu

You have probably seen that colored mulch in people's yards (the red and black types really jump out at you) and wondered, Is dyed mulch safe to use? If you have an organic bent, then your natural reaction (without knowing the specifics behind the product) is that you have no desire to handle something colored by chemicals -- and no desire to have potentially harmful materials leaching into the soil. So let's explore this issue in some detail.

Is Dyed Mulch Safe to Use?

Many homeowners ask if dyed mulch ("colored mulch") is safe to handle when mulching plants or safe to use around food crops. But the dye on colored mulch is less of an issue than the wood on which the dye is applied.

Dyes used in making colored mulch are usually vegetable-based and therefore harmless. Unfortunately, the question of whether dyed mulches are safe does not end with determining the composition of the dye.

The source of most dyed mulch is recycled wood. So far, so good. But the problem is that some of that recycled wood may be CCA-treated wood, which, used as a mulch, can raise the arsenic level in your soil. Although the use of arsenic in making pressure-treated lumber was largely banned after 2002, who is to say that a part of the source of the dyed mulch that you are buying is not old, leftover CCA-treated wood?

Enter the MSC Certification Logo, which certifies that a mulch or soil product is free of CCA-treated wood. MSC stands for Mulch and Soil Council. According to MSC's Product Certification program, "Certified mulches and soils can be found at major retailers and garden centers across the country." So look for the MSC Certification Logo if you wish to improve the chances that the dyed mulch that you are buying is safe for humans to handle.

Precautions to Take When Using Dyed Mulch (for You and Your Pets)

If the colored mulch that you are using is not certified, why would you wish to take a chance in handling it with your bare hands? It is recommended policy, therefore, to wear garden gloves whenever you will be touching this product. But what about our dogs and cats? Since we regard our pets as part of the family, guarding their health as we would guard our children's health -- and since they do not normally wear protective gloves -- it makes sense to keep them away from areas covered with such mulch.

Erecting a fence is one option for implementing this precautionary measure. One of the least expensive types of garden fencing that you can erect to keep pets out is a chicken-wire fence. This kind of fence is also very easy to set up, since all that it involves is pounding stakes into the ground and attaching the chicken wire to the stakes. To prevent animals from tunneling under it, however, it helps to dig a trench and partially bury the chicken wire in it. A good feature about taking this extra measure is that your fence will now double as a barrier to keep garden pests out, such as groundhogs and rabbits.

So much for the issue of dyed mulch, human health, and how safe it is for your pets. Whether or not colored mulch affects plant growth is a separate question.