The average lifespan of an outdoor plant box depends on materials, weather conditions, and maintenance. Typically, wooden plant boxes last 3–7 years, while plastic or metal ones can endure 5–15 years. Cedar and redwood resist rot naturally, extending longevity. Regular sealing, proper drainage, and sheltering from extreme weather help prolong durability. For eco-friendly options, recycled plastic or composite materials offer resilience. Investing in high-quality construction and routine care ensures your plant box remains functional and aesthetically pleasing for years. Choose wisely based on climate and gardening needs to maximize its lifespan.