A. We asked this question to one of our members, Gro-Bark (Ontario), which produces many varieties of mulch. The response is below for the products Gro-Bark produces.
We are unable to speak for all mulch producers, but the colourant Gro-Bark uses is an ironoxide colourant that is non-toxic to plants, animals and humans. If you visit the company website at www.gro-bark.com you will access a brochure on Colorbotics which is our colourant supplier. The direct link is www.gro-bark.com/brochures/gro-bark-enhance-coloured-mulches.pdf.