Can I Use Cedar Chips for a Worm Bin?

Compost worms such as red wigglers, or Eisenia fetida, do their work of composting your kitchen scraps by living surrounded by appropriate bedding material in their bin. Their habitat needs to meet their needs for a material that they can feed on in addition to their food scraps. Cedar chips contain tannic acid, resinous saps and essential oils that make them unlikely to be an appropriate bedding material for a worm bin.

  1. Bedding Parameters

    • Bedding refers to the loose organic material in a worm bin. The carbon in the bedding needs to be accessible to bacteria, which comprise a good part of the worms' diet. Improper bedding often leads to failure of the vermiculture operation. Bedding also needs to retain moisture, drain off excess moisture, allow air circulation and not be too coarse, according to Loren Nancarrow and Janet Hogen Taylor in "The Worm Book."
      Extension specialists recommend peat moss, soaked shredded cardboard, coconut fiber, aged manure, shredded non-glossy paper or newspaper, partly decomposed leaves or composted grass clippings.

    Wood Chips

    • Worm growers can also use wood chips and sawdust, state Nancarrow and Taylor, but it "must be mixed with some other bedding" because it dries out quickly.
      Asked whether cedar chips could be used as worm bedding, "the answer is 'no,'" replies Rhonda Sherman, extension specialist, North Carolina State University. "Aromatic wood is a no-no for worm bins."

    Cedar Concerns

    • Researchers consider cedar potentially toxic to earthworms. "Some trees, such as cedar and fir, have high levels of these naturally occurring substances (tannins). They can harm worms and even drive them from the beds," according to Glenn Munroe in "Manual of On-Farm Vermicomposting and Vermiculture."
      Thujone, an essential oil in cedar, repels moths, cockroaches, termites, carpet beetles and ants, according to researchers at Washington State University, and it, as well as the tannin, may be lead earthworms to recoil.
      However, some worm hobbyists report that a lack of microbial activity on cedar chips, rather than toxicity, makes them less than suitable for bin bedding. They report that cedar chips be admixed with other more suitable materials, so the cedar chips account for one-quarter of the total bedding.
      
"You should always test a small group of worms on the new bedding first," write Nancarrow and Taylor. "If the test group survives and is doing fine after 24 hours, there's a good chance that the rest of your worms will be fine, too."