Our back yard was landscaped in the ’80s or ’90s by a previous owner. We are somewhat on a hill and as part of this they used vertical railroad ties through all of the yard as retainers for dirt and planters. As a result there is a LOT of railroad ties in the yard. My concern is that we usually like to have a lot of edibles in our landscape. What is the danger from the chemicals in the ties having leached into the soil to eating food from fruits and veggies grown in the yard?
The Gardener’s Answer
Hi, Steve in Arizona: Railroad ties are treated with creosote, which is a general name given to a mixture of chemicals used as a type of wood preservative. As the railroad ties are replaced, they sometimes end up being used for retaining walls or edging in home gardens. The most common type of creosote is a product created when coal is heated to make gas. The Environmental Protection Agency classifies creosote as a possible carcinogen. There have been studies on the potential of plant roots to absorb these harmful chemicals and the results indicated more of a risk with tuberous vegetables. That being said, we know that creosote does leach into the soil but the older the tie the less creosote that remains. New ties should never be used in the garden so it is good that yours have been around for a while. You may want to designate a space for your vegetable/fruit garden that is as far away for the railroad ties as possible. Hopefully this is feasible and if not, container gardening may be the way to go. You could still incorporate edibles into the landscape in containers without the risk of absorption. The main goal is to not use them as borders in the edible garden, and if you have to you should wrap the ties in plastic so the roots will not come into contact with the ties.