Wood rot is a common issue for outdoor plant boxes, but with the right techniques, you can extend their lifespan significantly. Start by choosing rot-resistant lumber like cedar, redwood, or pressure-treated pine, which naturally withstand moisture. Apply a high-quality waterproof sealant or wood preservative to all surfaces, including hidden joints and undersides, to create a protective barrier against water penetration.

Ensure proper drainage by drilling holes in the bottom of your plant box and elevating it slightly with feet or bricks to prevent standing water. Line the interior with landscape fabric to reduce direct soil contact while allowing drainage. Regularly inspect your plant boxes for early signs of rot, especially in corners and joints, and address any issues immediately.

For added protection, consider using plastic liners or metal flashing in high-moisture areas. Reapply sealant every 1-2 years, or as needed based on weather exposure. By combining these preventive measures, you can enjoy beautiful, rot-free outdoor plant boxes for years to come.