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: Jonathan Foster, Home Horticulture Outreach Professional So, two separate building materials to consider, and it may depend on whether this garden bed is for edible plants or ornamentals. read more 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?