Metal planter boxes add a sleek, modern touch to urban gardens, but many gardeners worry about rust development. The short answer is yes, you should use a liner in metal planter boxes to prevent rust and extend their lifespan. While some metals like galvanized steel, aluminum, and corten steel have natural rust resistance, constant exposure to moisture and soil will eventually cause corrosion.
Using a liner creates a crucial barrier between the moist soil and metal surface. You have several effective options: heavy-duty plastic liners, pond liners, food-safe barrel liners, or even spray-on rubber coatings. Ensure whatever liner you choose has adequate drainage holes to prevent waterlogging, which can damage plant roots and accelerate corrosion from the inside.
For additional protection, consider these rust prevention methods: applying a food-safe sealant to the metal interior, using rust-resistant metal types from the start, or elevating planters to allow air circulation. Regular maintenance like inspecting for scratches and reapplying protective coatings will significantly extend your metal planters' life.
Remember that proper drainage is equally important - without it, water accumulates and increases rust risk regardless of liner use. With correct lining and maintenance, your metal planter boxes can remain beautiful and functional for many growing seasons in your urban garden.