When selecting planter boxes for urban environments, longevity becomes a crucial factor. Plastic planters, typically made from polyethylene or resin, offer excellent resistance to rot and insects. While they won't rust or corrode, they can become brittle and fade after several years of sun exposure. Modern plastics with UV inhibitors can last 5-10 years before showing significant wear.
Metal planters, particularly those made from corten steel, aluminum, or galvanized steel, provide substantial durability. Corten steel develops a protective rust patina that actually extends its lifespan to 15+ years. Aluminum resists corrosion naturally, while galvanized steel offers good protection, though eventual rusting may occur after 8-12 years depending on climate conditions.
Wood planters present the most variable longevity. Untreated softwoods may only last 2-3 years before rotting, while cedar and redwood contain natural oils that extend their life to 5-7 years. Pressure-treated lumber can last 10-15 years, though some gardeners have concerns about chemical leaching. The highest longevity comes from tropical hardwoods like teak, which can endure 20+ years with proper maintenance.
Each material requires different maintenance approaches to maximize lifespan. Plastic needs occasional cleaning, metal may require protective coatings, while wood typically needs regular sealing or staining. Consider your local climate, budget, and maintenance willingness when choosing between these materials for long-lasting urban planters.