Is it safe to use corrugated metal on the inside of the garden with wood treated with linseed oil on the outside of the metal?
Question:
Is it safe to use corrugated metal on the inside of the garden with wood treated with linseed oil on the outside of the metal?
Answer:
So, two separate building materials to consider, and it may depend on whether this garden bed is for edible plants or ornamentals. And “safe” is often a judgment call after learning about the risks involved.
1. Re: wood treated with linseed oil. It depends on whether the oil was raw or boiled. While raw linseed oil is food safe and generally shouldn’t be a problem in the garden bed, boiled linseed is mixed with a synthetic solvent to make it dry faster and is discouraged.
2. Re: corrugated metal in the garden. The concern here is potential leaching from the galvanization process. I was unable to find any peer-reviewed studies on the potential dangers here. But you aren’t the only gardener who has asked, as you’ll see here and here. Some Extension professionals are less concerned, others advise caution. While zinc does leach from the galvanized coating into any water present, that’s not my primary worry. Both plants and humans need zinc in minor amounts, and I suspect your plants would demonstrate zinc toxicity before it became an issue. However, cadmium is also a leachable component of the galvanization process. The risk under normal gardening circumstances is probably low, but because I can’t rule it out, I’m inclined to err on the conservative side and recommend using another material for your food plants and saving the metal planters for ornamentals.
Happy gardening.