Q: I have used wood chips from tree cutting services for some time under oaks and places grass will not grow with great success. I’m now wondering if I can use them in the flowerbeds versus using pine straw or colored mulch. Are they safe to use close to the house? Is there a treatment that should be applied?
A: There are so many more benefits than pitfalls to using wood chips as mulch, so confidently use it in flowerbeds and beneath trees and shrubs. It’s when people start thinking about using it in vegetable gardens that they may need to know a little more about their origins. Dyed or colored mulches are often made out of recycled wood, from materials like pallets. This wood could be pressure treated and/or treated with various chemicals at some point, so it’s probably best to not use this type of mulch around vegetable plants.
But don’t fear that mulch around your vegetables will rob them of nitrogen. That’s not true unless it’s mixed into the soil.
For flowerbeds- woodchips, pine straw, pine bark and dyed mulches are all okay to consider! One may win out over another simply because of cost or personal preference. Just don’t place mulch right up against the house. Come out with it at least a couple of feet. Spread similarly around the base of the tree, leaving at least 6-8″ of space/room for the trunk to breathe. And for mulch to be effective, depth is important: 1-2″ thick for beds, and 2-4″ deep around trees. Mulch will compress to half that in a year’s time.
Read more here too, from my friend Joe Lamp’l.