I love a good conspiracy theory. The more outlandish the better, too. If you can connect Justin Timberlake, Kim Jong-Un, and the moon landing – we might be best friends.
What I don’t love is a pervasive myth that keeps spreading via people who really, really should know better. Just recently a garden writer wrote an article stating that fresh wood chips should NOT be used as mulch because they rob the soil of nitrogen and are therefore bad for plants, especially trees and shrubs.
When there’s a landscape or gardening “truth” that can be verified using science, I turn to scientists. Scientists are always asking important questions and trying to understand our world better. Two researchers who have published very accessible books about science for the landscape are Jeff Gilman and Linda Chalker-Scott. In a post on Garden Rant talking about wood chip mulch, here’s what Dr. Chalker-Scott had to say in the comments:
From a scientific viewpoint, there are few drawbacks to using arborist wood chips but many benefits. It mimics what you might find in the duff layer of a forest – which is really what we should be shooting for in many of our landscapes that are based on trees and shrubs. I can say definitively that if wood chips are used as a topdressing and not worked into the soil they will not tie up nitrogen. We’ve demonstrated this in laboratory research as have others. For readers who would like a challenge, I’d invite you to read my review of the scientific literature comparing landscape mulches, published last December in the Journal of Environmental Horticulture. It also addresses many of the misconceptions held about wood chip mulches. You can email me for a free pdf of this article if you like.
From an aesthetic standpoint, fresh wood chips may leave a little to be desired, and if they just came from a brush job with thorns or poison ivy it may have some unpleasantness for you, the gardener. But for your plants? Bring on the wood chips if you want to suppress weeds, hold in moisture, and save a few bucks. The research does show that there might be an issue with shallow rooted plants like annuals and vegetables so don’t use chips there, but everywhere else? Game on.
I am not a scientist but I do my best to keep up with the latest research. If you want a landscape designed for beauty, function, and the well-being of your plants in mind, contact me!