Is it safe to make raised beds out of old galvanized metal roofing?
I am thinking of making some raised beds out of some old (60+ at least!) galvanized metal roofing we took off our cape in the 80’s. Should I worry about lead or cadmium leaching into my organic garden soil?
Lynne M. Holland, Horticulture and Social Media Professional
Since the panels you plan to use are so old I would be more concerned about structural rust than cadmium leaching. The leaching of these metals has happened over those sixty years. If you were still concerned about the lead I would then line the garden bed with old greenhouse plastic or some other kind of liner that has lots of drainage holes. If the raised bed is more than 14″ high I would line just the edges and not the bottom. The idea is to get a barrier between the metal and the soil. Here is a general reference of galvanized beds/raised bed construction.
Small amounts of lead in the soil is natural, but in places where there is older housing stock that may have had lead paint it is good to get a soil test of the soil you are using. If you are starting with a new soil mix (pro mix, compost, vermiculite etc) I would still do a soil test as you would want to know the pH and get fertilizer and amendment recommendations. There is a code for organic gardens so all recommendations are OMRI appropriate.