5 Things Nobody Tells You About Mulch – Gardenista

Many of us have destructive wildfires on our minds; so it’s smart to think carefully about your mulch choices, especially around your home and other buildings or wood structures. Of course most mulch is made from organic material so it is certainly flammable, but some materials are more so than others. In general, fine or stringy mulches ignite quicker. Pine needles top the list, as do shredded cedar bark and shredded rubber. The most fire-resistant choices are the inorganic types like decomposed granite, rocks and gravel. Pro Tip: Use fire-proof inorganic mulch materials within 5 feet of structures.

3. Mulch can be toxic.

No doubt that I love chocolate (maybe you do, too), so when I heard that there was such a thing as cocoa bean mulch I was intrigued—until I learned that this mulch, made from cocoa shells, is especially toxic to dogs. The lesson is to avoid using this mulch if you have curious pets.

Another questionable mulch is rubber mulch, which obviously is not organic so it doesn’t decompose or add anything beneficial to the garden. Plus, it can leach chemicals that can harm plants.

Free mulch can be acquired from tree or utility companies (yeah!), but make sure they’re not giving you the remains of a black walnut tree (boo!) as the toxic chemical called juglone in the tree can damage and even kill plants.

Last, dyed mulch—even that trendy black stuff—can be made with cheap dyes and from recycled treated wood like old decks, pallets, and crates that may contain nasty preservatives like creosote or chromated copper arsenate (CCA). CCA-treated wood can kill earthworms, beneficial insects, good soil bacteria, plus be harmful to people and animals who dig in it.