Urban planter boxes add greenery and life to city spaces, but their constant exposure to sun, rain, and soil begs the question: do they need sealant to last? The answer depends heavily on the material.
For wooden planter boxes, applying a sealant is highly recommended. Untreated wood is porous and will quickly rot from constant moisture contact. Use a non-toxic, water-resistant sealant specifically designed for outdoor garden use. Apply it to all interior surfaces, especially the corners and bottom, before adding a liner or soil. Reapplication every year or two is often necessary for optimal protection.
Plastic, metal, or fiberglass planters are inherently more resistant to moisture and generally do not require sealing. However, for metal boxes, checking for and treating any rust spots is crucial for longevity.
Regardless of material, a physical barrier is key. Always use a high-quality waterproof liner (with drainage holes) inside your planter box. This creates a crucial shield between the wet soil and the planter's walls, drastically reducing wear and tear.
In summary, while not all materials need chemical sealants, all planters benefit from proactive waterproofing. Sealing wooden boxes and using a reliable liner are the most effective steps to ensure your urban garden thrives for seasons to come.