Corten is a structural steel. This makes it an extremely long lasting material when using it as a planter. The slow rate at which Corten oxidizes gives it a unique beauty that will change over time, and thrive in any weather condition. Take a look at these Steel Planters in front of a Whole Foods Market in Basalt, Colorado. If you are planning for a large Corten Steel Planter installaion, it is important to know the rust runoff will bleed onto the surface where you place them. Steel rusts, it is what steel does, and it is what makes it a beautiful material. Sealing steel will create a regrettable maintenance headache. If you would like a maintenance free rust finish for Metal Planters, then fabricating in aluminum and a powder coated rust finish is the way to go. See this Southern California condominium project using aluminum planters with a rust powder coat.