
Six years ago Craig built a couple of 4×8 raised beds for a tidy vegetable garden where we could grow tomatoes, tomatillos, squash, raspberries and, sometimes, garlic.
He chose 1×6 redwood planks because they outlast by several years most other woods available in our Pacific Northwest region. But for the upright posts on either end of the bed, he chose less expensive and long-lasting chemically treated 4x4s (they anchor supporting wires that hold up raspberry canes). Like many gardeners, we worried that the chemically treated wood might leach into our veggies and fruit, and opted for the more expensive redwood surrounding the soil.
Now Oregon State University has come to our rescue with the release of initial results from a five-year ongoing study on whether and how far the chemical — copper — migrates into the soil.
These are the two questions they sought to answer:
- Do raised beds constructed from pressure treated wood leach copper into the soil?
- If leaching does happen, do the vegetables and herbs grown in the raised bed absorb the copper?
The best news is it doesn’t move into the plants at all.
Thank researchers at the university’s Department of Wood Science and Engineering for work that can put gardeners’ minds to rest when they choose copper-treated lumber for vegetable gardening.
Thank the Oregon State University Extension service for writing up a great and easy-to-follow article, which also goes into detail about the longevity of the wood.
Photos by Susan Palmer



