When building an outdoor plant box, choosing the right type of wood is crucial for ensuring durability and longevity. The best woods for this purpose are naturally resistant to rot, insects, and weathering. Cedar and redwood are top choices due to their natural oils and tannins, which repel pests and resist moisture. Cedar is lightweight, easy to work with, and has a pleasant aroma, while redwood offers superior strength and a rich color. Pressure-treated lumber is another excellent option, as it’s chemically treated to withstand harsh outdoor conditions. Avoid woods like pine or fir unless they’re treated, as they decay quickly. For a long-lasting outdoor plant box, prioritize cedar, redwood, or pressure-treated lumber to ensure years of use.