I’ve used tires as a stairway in my steep backyard. Would they be okay to use for plants I would eat: herbs, etc., or plants that produce squash, cucumber, strawberries, etc.?
Thanks for the question. To tell you the truth, the jury is still out. I have used them myself for retaining walls and stairs, and I have grown some food producing plants in them (potatoes for one) and have had great success. Typically the soil will get warmer in the tires and potentially too hot, and that might be great for some plants, possibly not so great for others.
There is, however, some concern that in the long term, tires could release toxins including zinc, hydrocarbons, and heavy metals. I would say that that concern could be also true for other materials like plastics of other kinds. Different than many plastics which are designed to contain food or water for human consumption, tires are not intended to contain food or their components eaten (be careful, Gonzo!), and so there are fewer studies with evidence.
I have done some research and found a similar sense of some folks doing it and some folks not being comfortable. People that are sensitive should likely stay away, if even from the way our concerns get into our blood. Others who are less concerned will likely have success. Here is an article that cites a variety of health risks from rubber pellets and specifically parts of tires in outdoor use. Get ready, it’s kind of intense and will bring up fears of other kinds. Here is another fantastic blog that answers the question elaborately and cites other research suggesting that there are actually very little risks as tires are very stable and DON’T BREAK DOWN (hence seeing them piled up everywhere).
My suggestion is that you consider your personal approach to such things and make a consistent stand. Cell phones? Car exhaust? Plastic water bottles? Tire planters? It’s hard to say. Sorry to leave it in your court and it is a crazy world.
Brandon Greenstein is the Home-Grower Program Director for Organic Growers School (OGS), developing new initiatives to provide services to home-growers. His background is in Renewable Systems, Earth Works, Energy, Water, and Permaculture, specifically providing consulting, design and technical services for the creation of integrated systems. He has been homesteading, including off-grid living and food production, in the western NC mountains for 20 years.