Corten Steel: Is It Safe For Gardens?
To speed rust your corten steel bed, combine 2 ounces of vinegar, ½ teaspoon of salt, and 16 ounces of hydrogen peroxide in a spray bottle. Shake the bottle vigorously to combine the ingredients. Wear gloves and goggles. Spray the entire metal planter box. Wipe it with a towel if the texture on the planter needs smoothing.