Not necessarily. A wooden urban planter box will not automatically rot within a couple of years, but it can if the wood stays constantly wet and the box is poorly designed. The real answer depends on the wood species, how the box is built, drainage, lining, climate, and maintenance. Under bad conditions, untreated softwood such as pine can begin to soften, stain, or show early rot in about two to three years. Under good conditions, cedar, larch, oak, thermowood, acacia, or properly treated wood can last much longer, often five to fifteen years or more.
Urban settings can be tough on planters because they often sit on balconies, rooftops, patios, or courtyards where rain, irrigation runoff, splashing, heat, and limited airflow keep moisture close to the wood. A planter that stands directly on a wet surface or has blocked drainage is far more likely to rot early. Soil pressed directly against untreated wood also holds moisture, and end grain can soak up water like a straw.
To prevent early rot, choose a rot-resistant or properly treated wood, raise the box slightly off the ground with feet or battens, and make sure there are generous drainage holes. Add a drainage layer if appropriate, use a breathable liner that still allows water to escape, and avoid overwatering. Sealing exposed end grain and applying a suitable exterior finish can help, but the finish must be maintained. For edible plants, use a food-safe liner and check local guidance before using pressure-treated wood.
So, is a wooden urban planter box going to rot within a couple of years? It might if it is untreated, poorly drained, and constantly wet. But with the right wood, good drainage, airflow, and simple maintenance, it can last well beyond a couple of years.