Safe oil treatment for above ground organic garden


I have a new 10’ X 3’ spruce above ground garden container with 4 inch walls. I want to grow organic vegetables. Is there an oil i could use on the outside of the planter so it doesn’t turn grey? I have been reading about raw or burned linseed oil but it doesnt seem like a good option for me


Thank you for contacting Toronto Master Gardeners.

As a community outreach group we are unable to give you specific product recommendations.

Looking through scientific literature I do not see any recommendations other than it is best not to treat the wood. A place that may have some answers for you is Landscape Ontario. They may know of some products; if there are any safe ones. Whatever you put on the wood will eventually leach somewhat into your soil.