 Dyed mulch is almost as bad. It's ugly, made of wood scraps which can be contaminated and has no carbon to nitrogen balance. Cypress plates and blocks out gas exchange and pine bark washes and blows away. What does stay in place and breaks down poorly won't help plant growth. Pecan shells also move around too much and fresh shells can attract fire ants. For more, take my online course on DirtDoctor.com.