Absolutely! Using a liner in your urban planter box is a highly recommended and effective method to prevent water, soil, and fertilizers from staining and degrading the wood. It creates a crucial protective barrier that extends the life of your planter significantly.
For best results, choose a durable, flexible liner material like pond liner, heavy-duty plastic sheeting, or even a specialized fabric grow bag inserted inside the box. Ensure you install it with proper drainage. Never let the liner form a solid, watertight basin at the bottom. Instead, line the interior, then use a drill to create drainage holes *through both the liner and the wood* at the bottom. This allows excess water to escape, preventing root rot and wood decay from trapped moisture.
Before adding the liner and soil, consider adding a layer of gravel or pebbles at the bottom for improved drainage. Finally, you can trim any excess liner material above the soil line for a neat appearance. This simple step of adding a liner protects your investment, keeps your planter looking beautiful, and creates a healthier environment for your plants.