I'm planning to build some raised garden beds for growing vegetables and I want to ensure they're food-safe. I was thinking of using untreated pine (CLS) and treating the wood myself with raw linseed oil. Will this approach keep the wood from rotting, or will I find myself replacing it in a few years? Also, if linseed oil isn't the best option, what alternative non-plastic finishes, sealants, or materials might I use to line the beds?
3 Answers
If you can find it, black locust or Osage orange are great options—they're really rot-resistant. Cedar would be a solid alternative too, and I recommend looking into white cedar or cypress if available.
In my experience, untreated pine usually starts to rot within a couple of years, though it might last 3 to 5 years depending on conditions. If you're aiming for longevity, you might want to consider cedar instead. I've read that modern treated lumber is also safe for raised beds now, so that's something to think about too.
I built raised beds using 2x12 untreated pine, but I coated them with polymerized linseed oil before putting them together. They held up for ten years in the northeast! This time around, I’m using corrugated metal roofing panels and cedar posts for my new beds.