Urban planter boxes bring greenery to concrete landscapes, but proper preparation ensures their longevity and plant health. The need for sealing or treatment depends primarily on your planter box material.
Wooden planter boxes absolutely require treatment to resist moisture decay. Use non-toxic sealants like raw linseed oil or specialized plant-safe wood preservatives. Avoid creosote and pentachlorophenol treatments which can harm plants. For wooden planters, applying 2-3 coats of sealant to interior surfaces significantly extends their lifespan.
Plastic, metal, and fiberglass planters typically don't need sealing, though drainage holes remain essential. Regardless of material, all planter boxes benefit from proper drainage systems. Drill multiple drainage holes in the bottom and consider adding a gravel layer beneath soil.
Many gardeners use plastic liners as an additional moisture barrier, particularly for wooden planters. Ensure any liner you use also includes drainage holes. The goal is balancing protection against rot while maintaining healthy drainage.
Before adding soil, thoroughly clean your planter box and inspect for any necessary repairs. Use quality potting mix specifically formulated for containers, as garden soil compactly too readily in confined spaces.
With proper preparation, your urban planter boxes will provide seasons of beautiful gardening while withstand weather elements. Regular maintenance checks will help identify when re-sealing becomes necessary, typically every 1-2 years for wooden planters in exposed locations.