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Why Wood Mulches Are BAD for Flower Gardens

Dyed wood mulches may look pretty, if you value uniformity of appearance and don’t otherwise consider yourself as having a gardener’s “green thumb”, but the more you know about gardening the uglier wood mulch looks . . and the less you use it. Based upon decades of experience I can attest that the only place a knowledgeable gardener might use dyed wood mulch is as a cover for a footpath, one where you don’t want anything to grow.

Why is using black dyed root mulch a bad idea and NEVER used to cover flower beds by well school gardeners? (But it is often used by landscapers, to “make things look finishd and pretty”, when dealing with consumers who aren’t gardeners.)

These links lead to articles that spell out why dyed root mulches are bad for flower gardens:  Is Your Mulch Miserable or Magnificant?  and The Best Garden and Landscape Mulches You Can Buy

Here is the shortened explanation of why, given the choice of using composted leaf mulch “as mulch” is the FAR better choice than using dyed wood or root mulches:

  1. Wood mulches “tie up” the available food in the soil, a process known as “nitrogen immobilization”. How? Wood is carbon, which is why it burns so nicely. However, carbon looks for nitrogen to bond with so it can break down. Wood mulch takes nitrogen right out of the soil. That’s the same nitrogen that plants love. I have seen this first hand when I had a stump ground in my hard. The resulting sawdust and fine chips wrecked havoc for years, making it impossible to establish new grass growth in the area.
  2. Dyed wood mulches are also suspect for having old pallet materials ground into their base materials.
  3. According to local gardening expert Mike McGrath (WHYY, Saturday A.M. “You Bet Your Garden; his site “GardensAlive.com”) his favorite “mulch expert” Ohio State Professor Emeritus Dr. Harry Hoitink, warns that dyed mulch is especially deadly when used around young plants or in brand new landscapes.
  4. Wood mulches can also host “artillery” or “shotgun” fungi, a nasty fungus that can turn adjacent structures black. I’ve seen it. I once shoveled root mulch from a path in our side garden alongside our house into a pile near the house, to begin laying in a brick path. I got busy with other projects and forgot about the root mulch until Carleen noticed black spots forming on the cedar siding. Dummy points for me.

Carleen religiously listened to Mike McGrath’s “You Bet Your Garden” broadcast on local public radio station WHYY, which on Saturday mornings followed the CarTalk show that I listened to – so we ended up with a bit of cross-training. My efforts in building the memorial garden have been guided, in substantial part, by the knowledge I gained about gardening from working directly with Carleen for almost four decades and from my knowledge of her values. When it came to gardening Carleen knew her business. Gardening was her passion and it showed. I have done and will continue to do my best to honor her values in my effort to build and maintain a memorial garden that truly honors her. In this case, on this issue – of whether “uniformity of apperance” (all public plantings on Main Street musl look alike) – I will not yield. This is entirely a case, in the most literal terms, of appearance over substance. Insisting that the memorial garden’s flower beds be buried under 2-4 inches of wood mulch goes against everything I’ve learned about gardening and Carleen’s values.